Prepare the cake by baking the chocolate cake according to package instructions. Allow to cool completely on a wire rack, about 30 minutes, then cut into 1-inch cubes.

In a large mixing bowl, whip the chilled heavy whipping cream on medium speed until soft peaks form, about 3-5 minutes. Optional: add powdered sugar for sweetness.

Layer the trifle by placing cubed chocolate cake at the bottom of the trifle bowl, followed by whipped cream, then cherries. Repeat layers until all ingredients are used, finishing with whipped cream.

Garnish the trifle with dark chocolate shavings and a few cherries on top.

Cover the trifle with plastic wrap and refrigerate for at least 2 hours or overnight before serving.