Apple Cake with Crumble

Method

1. Peel the Golden apples and cut into pieces, remove cores. Cut each piece into smaller pieces and place in a pot.
2. Add sugar, muscovado sugar, a little water, cinnamon, and lemon juice. Cook over medium-low heat for about 15 minutes, stirring occasionally.
3. Transfer the cooked apples to a blender and blend until smooth. Cover with plastic wrap (touching the surface) and refrigerate for a few hours until cold.
4. For the crumble: mix oat flakes, almond flour, granulated sugar, and salt. Add the melted butter and mix well. Add walnuts and mix again.
5. Spread the crumble mixture on a baking sheet lined with parchment paper in a thin layer. Freeze for 2 hours.
6. For the sour cream: mix cream, milk, and white vinegar. Let stand at room temperature for about 20 minutes without covering. Then cover with plastic wrap and refrigerate.
7. Peel and thinly slice about 1.5 apples (approximately 3 mm thick) for the cake.
8. In a stand mixer, cream the butter and sugar at medium-high speed until light. Scrape down the bowl.
9. Add the eggs one at a time, mixing well after each addition and scraping the bowl.
10. Add the prepared apple sauce, sour cream, and vanilla extract. Mix on medium-low speed.
11. In a separate bowl, whisk together flour, baking soda, baking powder, and salt.
12. Add the dry ingredients to the batter and mix until well combined. Increase speed slightly, scrape bowl, and mix briefly at high speed.
13. Fold in the sliced apples and walnuts.
14. Pour the batter into a buttered and floured cake pan. Level the top.
15. Crumble the frozen crumble over the cake batter evenly.
16. Bake at 160°C for 1 hour. Let cool.
17. Dust with cinnamon and powdered sugar before serving.