Making cakes is all about chemical reactions but you don't need to understand the science of baking in order to produce a cake.
Making cakes is all about chemical reactions but you don't need to understand the science of baking in order to produce a cake.

You do need to recognise that the recipe you're following has been written in a way that incorporates the fundamental rules of baking, and in order to achieve the desired result, you need to follow it carefully.
It's essential to weigh and measure ingredients accurately, and follow the instructions carefully. The ingredients need to be at the correct temperature before you start. For example, many baking recipes specify soft, chilled or frozen butter, and eggs at room temperature, in order to achieve a specific effect.
Also before you get under way, the oven needs to be preheated, its temperature needs to be accurate (or adjusted accordingly), and the shelves of the oven need to be in the right position. The tin you're advised to bake the cake in needs to be properly greased and/or lined according to the recipe's instructions.

There is some flexibility when it comes to selecting ingredients, but not much. As with other cooking, the best results come from using quality ingredients, but baking has the additional need for specific types of key ingredients, such as sugar.
Where caster sugar is specified, coarser granulated sugar or fine icing sugar are not acceptable substitutes as they'll create detrimental effects, such as a speckled finish or failure to hold air bubbles in the batter. Darker sugars such as unrefined molasses sugar or mucovado are great for baking but will give a darker colour, deeper flavour and moister texture than caster sugar, so need to be used in their appropriate recipes.
Similarly with flour: don't try to use strong bread flour in place of plain or self-raising flour because its gluten level is much higher. This will result in an uneven rise and a tough cake. You can, however, substitute plain flour for self-raising by adding sufficient raising agents.
With a few exceptions, the best cakes are made with butter. It has a superior flavour to margarine and, unlike oil or lard, can be beaten to incorporate air, resulting in a light, tender texture. Sweet baking usually requires unsalted butter, though there are notable exceptions such as shortbread. Lard is sometimes specified in traditional recipes to give a specific 'short' texture. Some moist cakes, often made with fruit and vegetables, specify the use of oil, which does have a lower saturated fat content, and in certain recipes, doesn't compromise the end results.

The way the ingredients of cakes and biscuits are combined depends on the type of batter or dough being made. How accurately you perform each step affects the end result.
Recipes requiring you to rub the fat into the flour will generally result in a dense mixture that has a moist, crumbly texture when cooked. The lightness of the mixture will rely on the raising agent (such as bicarbonate of soda or the use of self-raising flour) but for best results try to aerate the mixture by lifting the flour and fat up from the bottom of the bowl as you rub them together with your fingertips. If using a food processor be careful not to overwork the mixture (as for crumbles and scones).
'Creaming' requires you to beat butter and sugar vigorously until they're soft and creamy, using either an electric mixer or a wooden spoon. This aerates the mixture and gives it a mousse-like texture. The eggs then need to be incorporated slowly and steadily in order to prevent the mixture from curdling and to give the cake a fine, light texture.
'Folding' is a technique used in baking to combine mixtures of different consistencies. You might be asked to fold flour into a creamed mixture of butter, sugar and eggs, or to fold whisked egg whites into a batter. When folding, a large metal spoon is the ideal tool because the thin edge cuts through the mixture swiftly and cleanly. Remember you don't want to expel all the air you have just been trying to incorporate into the ingredients.

There are three types of sponge cake. The classic Victoria sponge relies on the creaming method in which butter and sugar are beaten together until pale, light and fluffy.
Whisked sponges contain no butter, and are therefore lower in fat. They can be made by either of two methods. Perhaps the easiest method is when whole eggs and sugar are whisked together in a bowl placed over a pan of gently steaming water. An electric whisk is a great advantage here as the speed of whisking needs to be steadily increased until the mixture is extremely thick. Using a hand whisk can take as long as 15 minutes.
The final method for making sponge requires the yolks and sugar to be beaten together and the egg whites whisked separately. The stiff whites are then folded gradually into the yolk mixture, alternating a little at a time with the sifted flour.
Fruit cakes are typically made by the creaming method, or in the case of the lighter traditional fruited cakes such as tea loaf, the melt-and-mix method (the butter and sugar are melted together, then left to cool before the other ingredients are mixed in to create a batter).
When making dense fruit cakes such as a Christmas cake, the batter needs to be heavy enough to suspend the dried fruit and nuts; if it's too thin the fruit will sink to the bottom. Another challenge comes from the sweetness of the dried fruit, which will scorch and turn bitter if the oven temperature is too high.
This is why traditional fruit cake recipes often require you to bake the cake slowly at a low temperature, and to line the inside and outside of the tin with paper: a double thickness of parchment paper inside, and several layers of newspaper secured with string outside.
The best of these cakes will be matured for at least a month, perhaps moistened with alcohol such as sherry, Madeira or brandy. The result is well worth the effort and, unlike other cakes, can be stored for a year or more.

Steamed puddings are a much-loved throwback to the days when households did not usually have ovens. They take longer to cook than mixtures baked in the oven do because the heat provided by the steam is gentle and indirect.
During cooking the water molecules in the pudding mixture vaporise, creating a soft, open texture, but it's essential that no water from outside the basin leaks into the pudding, otherwise the mixture will turn soggy.
For best results, cover the basin properly with a lid, or with a double layer of pleated greaseproof paper and a layer of foil, tied securely over the basin. Make sure the water is boiling when you add the pudding to the steamer, and keep it topped up to a level half-way up the sides of the basin during cooking, but do not open the lid of the steamer until after the pudding has been cooking for half an hour.

There are many ways to decorate a cake, some delightfully easy, others taking years of practice. The best decorations and fillings complement the cake underneath. Whipped cream and jam works a treat with mild buttery Victoria sponge, but would not be suitable for a dense, dark fruitcake laden with brandy. Consider too how long you need the decoration to last: fresh ingredients such as cream and soft fruit are fine if the cake will be eaten within a day or two.
Simple butter icings can be made from a mixture of beaten butter and icing sugar and a hint of flavouring such as vanilla or chocolate. They only need to be spread lightly over the cake (with other decorations such as coloured sprinkles or toasted nuts, if desired) and do not deteriorate quickly.
Whipped frosting - whether made from whipped cream cheese or Italian meringue - is one of the easiest ways to make a cake look festive and can be flavoured and coloured as desired. Frosted rose petals, chocolate scrolls or grated chocolate scattered over the surface of a frosted cake can make it look stunning.
Also simple to make is glace icing, a mix of sifted icing sugar, water and flavouring or colouring. When warmed it can be poured over the cake to create a pretty trickled effect. Try using two different-coloured icings for a mouthwatering finish.
Hard, white royal icing is traditional on dense fruit cakes and needs to be used in conjunction with almond paste (marzipan) to achieve a perfectly flat finish. Elaborate decorative effects are then added using specialist decorating tools such as piping bags and nozzles. A good alternative is to brush dense fruit cakes lightly with melted jam glaze and arrange nuts over the surface.

From crumbly buttery shortbread, to hard, dry Italian biscotti, biscuits vary widely in texture. The scrumptious chunky dough of a chocolate chip cookie, for example, isn't suitable for forming into the crisp outline of gingerbread men.
Most biscuits are made by the rubbing-in or creaming method, yet the ratios of ingredients are combined in such a way as to produce a wide range of styles.
The melt-and-mix method is used for biscuits such as brandy snaps and tuiles that are shaped after removal from the oven. They may be rolled or draped into as basket shape while still warm and malleable to produce the required decorative effect.
Remember that a reliable recipe will have been precisely calculated for best results. For example, using a larger egg than that specified could result in hard biscuits, while incorporating too much extra flour while rolling out the dough will make your biscuits tough and dry.
Follow recipe instructions for spacing the biscuit mixture on the baking tray. Some doughs are designed to spread and the biscuits will merge if placed too close together in the oven. Also remember that most biscuits need to be removed from the baking sheet as soon as they are set and left to cool on wire racks before storing in an airtight container.

Traybakes (bar cakes or 'slices' such as brownies and flapjacks), and American muffins, are some of the most convenient bakes because they're easy to serve, transport and eat.
The secret of producing good American muffins is to keep the dry and liquid ingredients separate until just before baking: don't leave the batter to stand. Also, combine them as quickly and gently as possible in order to give a light texture.
Mixing flapjacks is very easy as their finished texture doesn't rely on the aeration of the mixture. Their fast melt-and-mix method is good for beginners, especially children learning to cook.
Although flapjacks are often thought of as healthy cakes, and contain a high content of nutritious oats, they are high in fat, which helps hold the mixture together. One way of reducing the fat content of flapjacks is to replace some of that butter with mashed banana, or a puree of dried apricots or prunes.
Crumbles are another type of bake often considered healthy, though a traditional crumble topping is essentially a type of pastry. As when making pastry, it is a good idea to leave the crumble to rest for 20-30 minutes before scattering it over the fruit. To vary the topping, replace a portion of the flour with rolled oats or barley, coarse oatmeal or crushed amaretti biscuits. Adding finely ground nuts such as almonds or hazelnuts allows you to reduce the quantity of butter as nuts also contain fat to keep the mixture moist.
Remember the thickness of the crumble will depend on the dimension of the baking dish. A wide shallow dish will result in a thin, crisp crumble while a deep dish with smaller diameter will give a thick crumble with a chewier texture near the fruit. For a professional finish, pile the fruit high in the centre of the dish (as for a fruit pie), then as it cooks it will flatten rather than sink.

It's best to use the size of cake tin recommended by the recipe you're following rather than select you own. The shape and dimensions of a tin radically effect the cake's cooking time and the author will have chosen the type of tin that best gives character to the cake.
That doesn't mean you need buy every tin in the shop, but a mix of round, sandwich, square, rectangular, loaf, springform and bun/muffin tins, plus one or two baking trays, will enable you to cook a wide range of recipes. As you become more confident you may want to expand the range with specialised tins such as Swiss roll and decorative ring pans.
Cheap cakes tins are a false economy: buy the best and heaviest you can afford and they will last you a lifetime if properly washed and dried each time you use them. Non-stick cake tins are also useful when it comes to turning out cakes, but they often still need greasing and lining, and the nonstick lining can deteriorate over time. An increasing range of flexible silicone baking containers are also available.

Cakes are best stored in airtight tins rather than plastic boxes, and should not be stored in the same container as crisp biscuits, or the latter will turn soggy. Once a cake has been cut, the cut surfaces will start to dry. Covering them with a piece of foil minimizes the effect.
The type of decoration will affect the potential storage time, as it may deteriorate at a faster rate than the cake. Undecorated cakes can be frozen for up to three months if tightly wrapped. It's also possible to freeze iced cakes: freeze them unwrapped just until the icing is firm (otherwise it will start to dry out) then carefully wrap the cake in clingfilm, plus an outer layer of foil. Remember to defrost the cake slowly in the refrigerator to prevent water beads or condensation forming on the surface.
You can freeze cooked biscuits for up to one month. Unbaked dough can be frozen for up to one month, or chilled for three days. Putting a few cubes of sugar in a biscuit tin helps keep them crisp. A handy trick is to refresh previously baked biscuits by heating them in a low oven for five minutes before serving.

Chocolate brownies by Lesley Waters (video recipe)
Victoria sponge with strawberry jam by Lesley Waters (video recipe)
Christmas pudding by Lesley Waters (video recipe)
Chunky apple crumble by Lesley Waters (video recipe)
Basic butter icing by Louisa Carter
Lemon and passion fruit shortbreads by Jo Pratt
Carrot and olive oil cake by Celia Brooks Brown
Chocolate mousse in a tuile box with fresh raspberries and vanilla cream by James Martin