My mother in-law in Moscow is really good at making this cocoa flavored sweet. It's a nostalgic sweet for Russian people, and it has a simple homemade taste. Please give this a try when you have leftover bread.
Make panko first. Break up the sliced bread into small pieces, put in a food processor and make panko. I use a hand blender with a chopper attachment at home.
Set aside 1 cupful of panko. Put the rest of the panko in a bowl, add the cocoa powder, and mix well.
Melt the butter, and mix in the condensed milk and the milk to it. Add that to the panko, little by little, and mix.
When everything is mixed together, roll the mixture into barrel-shapes.
Coat the barrel-shaped dough with the panko from Step 2.
Place the breadcrumb-coated dough in a plastic container, chill in the fridge overnight, and it's done. You can keep it in the freezer as well.
This is the sliced bread I used this time. I think you can make this with store-bought panko too, but adjust the amount of liquid as they are very dry.
This is the condensed milk I used. It was a light type condensed milk, and I thought it wasn't quite sweet enough.
Story Behind this Recipe
My mother in-law, who lives in Moscow, is really good at making this sweet. I recreated it based on the taste I remember and a recipe in Russian. 'Pirozhnoe' is cake, and 'kartoshka' is potato in Russian. The name of this sweet comes from its shape resembling to a potato. Please bear in mind that you will make tons of them using the amounts of ingredients in this recipe.
Actually, they used to use 'petunia cookies' to make it, not with breadcrumbs. Apparently, you need this poor quality 'petunia cookies (a.k.a 'Soviet Union cookies)' that were commonly used in the Soviet Union era to make a real taste of this sweet. So I took my husband's advice and substituted with breadcrumbs to make this.