Now comes the stuffing part.
You can fill them with what you like. The only condition is that the filling is thick and sticky, not runny.
I chose condensed milk. Take a can of condensed milk, place in a pot and bring to the boil. It must be completely covered with water, otherwise it explodes! Let simmer for about three or four hours. If the water level drops in the meantime, add a little more hot water, so that the can is covered at all times.