1.
One hour before baking, peel and cut the apples (the crumble will be sweeter if you use red apples). Let them soak in a bowl with the walnut milk.Add
cider vinegar.
2.
Meanwhile, prepare the crumble: combine the flour, ground almonds and sugar in a bowl. Mix with a spoon. Cut the cold butter, fresh from the fridge, into cubes and add it to the bowl. Use your hands to combine until the mixture has a crumbly texture. Let it sit in the fridge for about 30 minutes.
3.
Preheat the oven to 356 °F.
4.
Spread the apples over the greased pan. Pour in some walnut milk and sprinkle the apples with a little cinnamon.
5.
Spread the crumble over the apples, aiming to cover them completely.
6.
Bake for about 30-40 minutes until the top is lightly browned. Serve warm.