This is a slightly unusual recipe for charlotte with apples. Apples are laid into the dough, and a filling of sugar and cinnamon is sprinkled on top. The finished charlotte is obtained with a caramel crust.
Make the nut-cinnamon filling: In a bowl, combine 1 glass crushed walnuts, 1/4 cup brown sugar, 1 teaspoon ground cinnamon, 2/3 cup flour, and 4 tbsp softened butter. Stir until smooth.
Prepare the apples: Peel, core, and slice the 4 apples. Sprinkle with 2 tbsp white sugar.
Preheat the oven to 180°C (356°F). Grease a baking sheet with high sides (35×25 cm).
Make the cake batter: In a large bowl, whisk 1 glass (180-200g) softened butter and 1 1/2 cups white sugar on high speed until combined. Add 500g sour cream, 1 tbsp baking powder, 1 teaspoon baking soda, 2 teaspoons vanilla extract, 4 eggs, and 2 1/2 cups flour. Beat on low speed until smooth, then increase to medium speed and beat for 1 minute.
Pour the batter onto the prepared baking sheet. Arrange the apple slices on top.
Spread the nut-cinnamon filling evenly over the apples. Bake for 45–50 minutes.