Mix eggs and sugar in a bowl. Beat the mixture with a mixer until it becomes smooth and fluffy. The eggs should increase in volume by about 2-3 times. Without stopping beating, gradually add sifted flour and baking powder. Add a glass of finely chopped walnuts to the ingredients and gently knead the mass from the bottom up.
Pour the dough into the form and bake in a preheated oven for 40 minutes. Remove the form with the biscuit from the oven, turn it upside down. Leave the biscuit until it cools completely. Cut the finished cooled nut biscuit into two parts with a special pastry thread or a long serrated knife.
Pour cold sour cream into a chilled bowl, add sugar and beat thoroughly with a mixer to achieve a fluffy, airy cream consistency.
Spread some of the cream on the bottom layer, spreading it evenly over the surface. Place the second layer flat side up and spread some cream on it as well. Sprinkle the cake with chopped nuts. Put the finished dessert in the refrigerator so that it soaks and the cream thickens.