Roll Cake:
Generously sprinkle a clean kitchen towel with powdered sugar. Carefully turn the cake pan upside down onto the towel. Gently remove parchment paper. Trim off crusty edges if necessary.
While the cake is still hot, gently roll the cake with the towel from the narrow end (don’t make it too tight and don’t press).
Cool on a wire rack for at least 30 minutes.
Gently unroll the cake and spread cold custard all over, leaving about an inch and a half at one of the short ends (not the one you start rolling on).
Carefully roll the cake back up (starting with the side that has the filling to the edge) and place the cake on the serving dish, seam side down.
Ganache:
Prepare Ganache:
Bring heavy cream to boil, but be careful not to let it actually boil.
Pour boiling cream over the chopped chocolate and stir until melted. Let it cool for a few minutes.
Pour ganache over the top of the cake roll and gently spread it around.
Enjoy your Boston Cream Cake Roll!