Apple crumble with walnuts
Preheat the oven to 180C/350F/Gas 4 (160C fan).
Peel and core the apples, then cut them into thin slices. Place in a small flameproof casserole with the lemon juice, sugar and six tablespoonfuls of water. Bring to the boil, then place in the oven and cook for about 20 minutes, or until the apple is tender but has not fallen to a pulp.
Put the dry topping ingredients in a mixing bowl and rub in the butter until it is evenly distributed and the mixture has formed small clumps. Spread the mixture evenly over a baking tray and bake for about 20 minutes, or until golden-brown and crisp.
Stir to break up the crumble and sprinkle over the hot apple.