Butter and ovenproof dish. Lay the prepared apples in the dish.
Mix the sugar, flour, baking powder and lemon zest. Melt the butter and stir into the flour mixture, mixing well. Spoon the mixture over the apples then scatter over the flaked almonds.
Bake at 200 C, 180 Fan Gas 6 for 30 minutes, or until cooked. Let the pudding cool a little when it comes out of the oven. Dust with icing sugar if you like before serving.