Alexandra Dudley shows us a recipe that she looks forward to making every year. Serves 12 7large sweet potatoes (approx. 1.5kg) 70g finely grated Grana Padano, plus extra to top 1 large bunch of sage Olive oil Salt 100g precooked chestnuts 200g taleggio 600ml double cream 250ml milk ¼ fresh nutmeg, finely grated Salt and pepper Preheat the oven to 160 degrees fan setting Peel the potatoes and slice thinly into roughly 3m slices then add to a large ovenproof casserole dish (approx. 30cm diameter)