Put the bread flour, cake flour, sugar, salt, years and cocoa power in a bowl. (Add the salt and sugar in separate parts of the bowl, and add the yeast to the part near the sugar.)
Combine the egg and milk and warm it up. Add this to the bowl, aiming for the part with the yeast. Add the melted chocolate too.
Mix it all together in the bowl with your hands. It will be sticky, but it's fine if it just comes together in a clumpy ball.
Take the dough out onto a work surface and knead it for a while. When it has a bouncy texture, add the butter and keep kneading.
When the surface is nice and smooth, round the dough off into a smooth ball, place in a bowl, cover with plastic wrap and leave to rise. (About 50 minutes in a warm location.)
It's finished rising.
It seems a shame to do this, but just punch it down with your fist to deflate it and release the excess gases. Let it rise again (about 20 minutes.)
As long as it rises a bit even if it's not puffy and cute, it's fine. Now the 1st rising is really complete.
Divide into eight 50 gram portions and round off each portion. Cover with a tightly wrung out moistened kitchen towel and rest (for longer than usual, about 30 minutes).
Fill a piping back with the chocolate cream. (See Recipe ID: 1054580 for the chocolate cream recipe.)
Press down lightly on the dough to deflate it. Roll out into an oval shape with a rolling pin.
Pipe out the cream as shown in the photo.
Bring the dough over from the top to wrap the cream, and press the dough down around the cream so it won't come out.
Make vertical cuts in the dough with a pastry cutter.
Brush the cut part with beaten egg.
Roll up from the far side so that the end of the dough is on the bottom.
Make 8 rolls, and line them up on a paper-lined baking sheet for the 2nd rising. (40 minutes in a warm location.)
The 2nd rising is finished. Brush the tops with beaten egg.
Bake for about 13 minutes in a pre-heated 210°C oven and they're done.
Story Behind this Recipe
I saw this at a certain bakery, and fell in love with it at first sight.
Bread dough with chocolate and cocoa kneaded into it doesn't stretch or rise well, and has a tendency to dry out easily. So I set the rising and resting times longer than usual. There are lot of steps and it takes time to make this, but they are worth it. Please give them a try.