Ingredients
For the fool:
300g/11oz blackberries
75-100g/3-4oz sugar
juice of 1 lemon
120ml/4fl oz double cream
50g/20z mascarpone or extra 50ml/2fl oz double cream
For the hazelnut biscuits:
375g/13oz caster sugar
250g/9oz unsalted butter, softened
2 size 1 eggs
1 tsp vanilla essence
275g/10oz plain flour
1 tsp bicarbonate of soda
1 tsp baking powder
150g/5oz hazelnuts, roasted, peeled and chopped

Method
1. To make the fool, reserve a handful of blackberries for the garnish and purée the remainder with the sugar in a blender then rub through a fine sieve. The resulting purée should be thick. The quantity of sugar relies heavily on the natural sweetness (or lack of it) of the blackberries.
2. Add the lemon juice, then taste and adjust the flavouring.
3. Whisk the double cream to just soft peaks, not any thicker.
4. Soften the mascarpone by beating by hand and then whisk the two gently together. It is important not to overbeat this mixture. It can be taken too far and then the fool will have a grainy texture.
5. Finally, fold this mixture together with two-thirds of the purée. The remaining one third should be kept aside until assembly.
6. In a sundae dish or wine glass, place a few blackberries tossed in a spoonful of the reserved purée. Fill the glass half-way with the creamy mixture. Place a thin layer of the purée on top of this layer before filling the glass with more creamy mixture.
7. Fill the other dishes in the same way.
8. Chill in the fridge for at least 2 hours to firm up the mixture.
9. Preheat the oven to 180C/350F/Gas 4.
10. Grease a baking sheet.
11. To make the biscuits, cream the sugar and butter together until light and fluffy.
12. Add the eggs and vanilla essence and mix again until it is all incorporated together.
13. Sift together the flour, bicarbonate of soda and baking powder.
14. Fold this mixture into the butter/egg mixture.
15. Finally, fold in the hazelnuts.
16. Using a spoon, drop spoonfuls on to the baking sheet, leaving space between them to allow for spreading.
17. Bake in the oven for about 8 minutes until golden brown.
18. Remove from the baking sheet and leave to cool on a wire rack.
19. Serve the mousse with the hazelnut biscuits and garnished with the reserved blackberries.