Cut apples into tiny pieces. Submerge them into a pot of water so they become nice and mushy. This will also help the crumble to be less tarty as well. 

For the crumble topping, I was advised to start with 80-100g of butter, to which flour and sugar is added until the mixture is quite dry, and good to taste.

Into your mould, place the apple and berries, and cover with the crumble on top.

Bake in the oven at 180 degrees until golden on the top