Mix all the crumble ingredients and process into fine crumble and chill for about 1 hour.

In the meantime, peel and quarter the apples, cut out the core, cut into the round side, drizzle with lemon juice and set aside.

Whisk all the ingredients for the sour cream.

Grease and flour a springform pan (26 cm). Preheat the oven to 180 degrees top-bottom heat.

Put 2 / 3 of the crumble on the bottom of the pan, push up a small edge and press the bottom down.

Put 1 / 3 of the sour cream on the base and smooth it out, then spread the apples on top and pour the rest of the cream on top.

Spread the remaining crumble on top and bake in the oven for about 70 minutes.

After baking, let cool in the tin and dust with icing sugar before serving.

I put aluminum foil on the cake 20 minutes before the end of the baking time, otherwise it would have become too dark.

The sour cream was still quite soft after cooling and next time I'll stir in 2 packets of almond pudding.