On a lightly floured working surface, roll out the dough until you have a 5mm high rectangle. From the short side it must be 30cm and the long side it ha to have a little less centimeters than the length of the circumference of the mold in which you are going to put it (I used a 24cm diameter mold, so the long side measured 70cm).
The calculation of the circumference is easily done (even for a dumm like me): multiply the diameter of the mold by 3.14. At the risult subtract five six centimeters which will be recovered with the leavening.
Once the dough is rolled out at the right measure, pour and spread the cold chocolate cream over the entire surface.
Roll the rectangle on the long side until it like a roulade. Wrap it in a lightly floured plastic wrap and put in the fridge for a couple of hours.
Use a sharp knife to gently cut the roll in half lengthwise, starting at the top and finishing at the seam, essentially dividing the log into two long even halves, with the layers of dough and filling visible along the length of both halves.
With the cut sides facing up, gently press together one end of each half, then lift the right half over the left half. Repeat this process, but this time lifting the left half over the right, to create a simple two-pronged plait.
Carefully lift the babka into a round pan with a heatproof little bowl so that the babka will not "crash" on itself during risen.
Let rise for a couple of hours.
Preheat oven at 160°.
Bake for 45'