Preheat your oven to 350°F (175°C).

In a large mixing bowl, cream together the butter and sugar until light and fluffy.

Add in the eggs one at a time, mixing well after each addition. Then, stir in the vanilla extract.

In a separate bowl, sift together the flour, cocoa powder, baking powder, and salt.

Gradually add the dry ingredients to the wet mixture, mixing just until combined.

Pour the batter into a greased 9-inch round cake pan and bake for 25-30 minutes.

Once baked, remove from the oven and cool for 10 minutes before transferring to a wire rack.

Whip the heavy cream with powdered sugar until it forms soft peaks.

Cut the cooled chocolate cake into cubes.

Begin assembling the trifle: alternate layers of cake cubes, cherries, and whipped cream in a trifle dish or individual glasses.

Finish with a layer of whipped cream on top and garnish with chocolate shavings.

Chill the assembled trifle in the refrigerator for at least 2 hours before serving.