Combine Dry Ingredients: In a large bowl, whisk together 230 grams of flour, 1 teaspoon of baking powder, and a pinch of salt.

Add Butter: Add the 90 grams of cold, cubed butter into the dry ingredients. Using your fingers or a pastry cutter, mix until the butter is well incorporated and the mixture resembles coarse crumbs.

Incorporate Wet Ingredients: Add the 2 egg yolks and 40 grams of sugar. Knead gently until the dough starts to come together. If the dough feels too dry, add a teaspoon of cold water. Form the dough into a ball, wrap it in plastic wrap, and refrigerate for at least 30 minutes.

Peel and Slice Apples: Peel, core, and slice the apples into thin wedges. Place them in a bowl and toss with 4-5 tablespoons of lemon juice and 40 grams of sugar. This will add a tart flavor and prevent the apples from browning.

Beat the Egg Whites: In a clean bowl, beat the 2 egg whites until they reach soft peaks. Gradually add 40 grams of sugar while beating until the egg whites form stiff peaks.

Add Remaining Ingredients: In a separate bowl, mix 400 grams of yogurt or sour cream with 1 teaspoon of vanilla extract and 30 grams of cornstarch. Fold in the beaten egg whites gently until fully incorporated.

Roll Out the Dough: Remove the dough from the refrigerator. On a lightly floured surface, roll out the dough to fit a 20 cm (8-inch) baking form. Transfer the dough into the greased form and press it evenly along the bottom and sides.

Layer the Apples: Arrange the prepared apple slices evenly over the dough, creating a compact layer of apples.

Pour the Sour Cream Mixture: Pour the sour cream mixture over the apples, making sure to spread it evenly to cover all the apple slices.

Bake: Preheat the oven to 180°C (350°F). Bake the pie for 40-45 minutes, or until the top is set and lightly golden. The edges of the dough should also be golden brown.

Check for Doneness: The sour cream layer should be set but still slightly jiggly in the center when the pie is done. If the top begins to brown too quickly, you can cover it with aluminum foil for the remaining baking time.

Cool: Remove the pie from the oven and let it cool in the baking form. Once the pie has cooled down, you can refrigerate it for a couple of hours to help it set further before serving.

Slice and Enjoy: Once cooled, slice the pie and serve. You can garnish with powdered sugar or serve it with whipped cream for an extra touch of sweetness.