Preheat the oven to 190°C.
Grease the loaf pan with a little oil.
Roll out the yeast dough into a rectangle and spread the brownie batter on it.
Roll up the dough from the short side.
Cut the roll in half lengthwise and twist both parts together.
Place the dough in the loaf pan and let it rise in a warm place for about 45 minutes.
Bake the babka for 30-40 minutes. If the surface gets too dark, cover with a piece of aluminum foil.