Truffle sour cream cake

 1 egg is mixed with 1 tablespoon of sugar, add 1 cup of sour cream, baking soda extinguished with vinegar - 0.5 tsp (1 tablespoon of vinegar), 1.5 cups of flour, and 1/2 pack of cocoa (standard 200g), mix everything well and place in a mold greased with oil and sprinkled with breadcrumbs or flour. Bake in a not hot oven for 35-40 minutes.
The finished cake is cut into 2-3 layers and each is smeared with cream:
There are two options for cream: 1) butter "truffle" - 200g of butter + 1/2 cup of condensed milk, beat and add 1/2 pack of cocoa, mixing well.
2) sour cream coffee - 1 cup of sour cream + 1 cup of sugar, add instant coffee to taste and heat, stirring, bring to a boil, but do not boil, add 50g of butter. Beat the cream well.
I have sour cream cream, but without coffee.
The top is covered with glaze: 1 tablespoon of cocoa, 1 tablespoon of sour cream, 1 tablespoon of sugar, 1 tablespoon of butter - heat everything, mix well until homogeneous consistency and quickly pour over the cake.
Enjoy your meal!