For the sweet potato fries, pre-heat the oven to 220C/200C Fan/Gas 7.
Wash the sweet potatoes and pat dry. Cut each sweet potato in half lengthways. With the flat side down, cut each half into 4-6 long wedges, depending on the size of your potatoes.
Place the wedges on a tray and pour over the olive oil, sprinkle over the spice mix, if using, and season generously with salt and pepper. Use your hands to mix the wedges in oil and seasoning. Spread the wedges out into a single layer and bake for 30 mins until crisp and golden, turning halfway through.
For the sweet potato jackets, pre-heat the oven to 200C/180C Fan/Gas 6.
Wash the sweet potatoes and pat dry with kitchen paper. Rub generously with olive oil and place on a baking tray. Season generously with salt and black pepper. Bake for 45 mins until the skin is crisp and the potatoes are soft to touch.
Remove from the oven and carefully cut in half to expose the soft potato. Top with a knob of butter and sprinkle over chopped chives or spring onion, if using. Season with salt and pepper.
To make the sweet potato mash, peel the sweet potatoes and cut each potato into 8 even-sized chunks. Tip into a pan and cover with cold water. Bring to the boil, reduce the heat and simmer for 20 mins, until the tip of a knife easily slides through.
Drain and return to the pan over a low heat. Add the butter and pour in the milk a little at a time while mashing the potatoes until smooth. Stir through a pinch of salt and a few generous grindings of black pepper.
Spoon into a warmed serving bowl, season with salt and pepper and scatter over fresh parsley, if using.