For the crumble mix the light brown soft sugar, plain flour and the wholemeal plain flour together
Add the butter to the bowl in chunks or cubes, then using your fingers, rub it into the flour and sugar until it resembles breadcrumbs. You can also do this in a food processor if you prefer
Peel and chop the apples into small pieces and place in a bowl. Use an apple cutter to do this quickly and avoid the apples browning. Or you can put a squeeze of lemon juice into a bowl of water and add the apple chunks to it as you cut them. Drain them off when you're done
Add the sultanas, light brown soft sugar, cornflour, cinnamon, mixed spice and nutmeg to the apples and stir them all together
Put the apple mix into a baking dish (ideally 31x21cm)
Spread the crumble topping over the fruit and bake it for 45 minutes until golden and bubbling
Serve warm, or leave to cool fully, cover the dish with cling film and store in the fridge for up to 3 days
Notes
Mixed spice is a British spice blend containing Cinnamon, Coriander Seed, Nutmeg, Clove, Pimento, Ginger. If you can't get hold of it, use a Pumpkin Spice mix instead