Divide the egg whites and yolks. Smash the chocolate with the butter put them to melt in a water bath. Beat the egg whites with a pinch of salt on foam, as kisses. While away in a deep pot put sugar, egg yolks, sour cream and vanilla and beat with a mixer. Already melted chocolate and butter begin to send down a thin stream without stopping the mixer. After a homogeneous mixture and we poured the entire chocolate comes the egg whites and flour. Alternating flour, egg whites and mix gently with a spatula to not fall egg whites. After we have added all amount of flour and egg whites begin to spread dough into shapes for muffins and put in the oven to bake. Bake 20-22 minutes. Obtained very delicious cakes with crispy crust tseluvchena and moist inside.