1. Preheat oven to 180 °C (350 °F).
2. Line the bottom of a 20-cm springform pan with parchment paper. Coat the sides of the pan with cooking fat.
3. In a bowl, mix all dry ingredients. Set aside.
4. In a bowl, mix the melted butter and sugar. Add eggs and vanilla extract. Mix.
5. Add dry ingredients. Mix until just combined.
6. Add half the apple slices. Mix.
7. Pour into pan. Cover with remaining apple.
8. Bake for 70 to 75 minutes (or until a toothpick inserted comes out clean).
9. Remove from oven. Let stand 30 minutes before serving.
10. Serve with cinnamon sugar sour cream.

*You can find cinnamon sugar in the spices section. You can also make it by mixing ¼ cup of sugar and 1 tsp. of ground cinnamon.