Homemade Kefir Cake with Boiled Condensed Milk

In a bowl, combine the eggs, sugar, and a pinch of salt, mixing well. Pour in the vegetable oil and warm kefir. Sift in the flour, cocoa powder, baking soda, and baking powder, add them to the liquid mixture, and stir thoroughly until smooth.

Transfer the batter into a 22–24 cm baking pan, lined with parchment paper on the bottom or greased and lined with foil. Place the pan in a cold oven, turn on the heat to 180 °C, and bake for about 50 minutes. Check for doneness with a wooden skewer.

Let the cake layer cool completely. If desired, trim the top — it can be crumbled to use as a coating for the cake.

For the frosting, stir the boiled condensed milk until smooth, add the sour cream, and gently combine with a whisk or spatula without using an electric mixer to prevent the frosting from becoming runny.

Cut the cake layer into 2 or 3 parts, spreading the frosting generously between them. Set aside a small amount of frosting to coat the sides. Sprinkle the cake with the crumbs made from the trimmed pieces.