Cherry Pie with Meringue Topping

Cherry pie topped with protein foam
Ingredients:

Dough:
300 g of flour (about 2.5 cups)
150 g of margarine (about 2/3 cup)
2 egg yolks
50 g of sugar (about 1/4 cup)
2-3 tbsp sour cream (use thicker, tangier Eastern European-style sour cream if available)
2-3 tbsp breadcrumbs
Filling:
500 g of cherries (about 1.1 lbs)
500 g of sugar (about 2.5 cups)
vanillin
Egg White Foam:
2 egg whites
50 g of powdered sugar (about 1/4 cup)

Mix the margarine with the flour, then add the sugar, egg yolks, and sour cream, and knead the dough. Roll the dough into a disc and press it into a greased cake pan; prick the dough with a fork. Sprinkle the pan base with breadcrumbs, add the pitted cherries, and top the cherries with a mixture of sugar and vanillin. Bake in a preheated oven for 30 minutes. Then pour the whipped egg whites mixed with powdered sugar over the cherries and return the pie to the oven. Remove the pie when the foam turns golden brown.