Sour cream 15%
Melt the butter. In a bowl, combine flour, sugar, cocoa and sour cream, soda. Pour in the butter and cut the bananas into 2 cm slices. Add two eggs. Beat the dough with a mixer until smooth.
Prepare the mold, grease it with oil. The dough will rise well, so leave at least 1 cm from the top edge. Alternatively, you can cut the banana into pieces of 10 cm and gently insert into the dough. Bake at 160 degrees. Cool the finished cupcake a little on a wire rack (up to 90 degrees) and wrap it with a film for a day, along with the mold. Keep in the refrigerator.