Preheat your oven to 375°F (190°C). Line a 15x10 inch baking sheet with parchment paper, ensuring the paper extends over the edges.
In a large mixing bowl, beat the eggs and granulated sugar with an electric mixer on high speed until thick and pale, about 5 minutes.
In another bowl, sift together the flour, cocoa powder, baking powder, and salt. Gently fold the dry ingredients into the egg mixture until just combined.
Pour the batter into the prepared baking sheet and spread it evenly. Bake for about 12 minutes, or until a toothpick inserted into the center comes out clean.
Remove the cake from the oven, carefully invert it onto a clean kitchen towel (remove the parchment paper), and roll it up along with the towel. Let it cool completely in this rolled position.
Meanwhile, whip the heavy cream, powdered sugar, and vanilla extract in a mixing bowl until soft peaks form.
Once the cake has cooled, gently unroll it and spread a generous layer of whipped cream over the cake. Spoon the cherry pie filling evenly over the whipped cream.
Carefully roll the cake back up, this time without the towel. Wrap it in plastic wrap and refrigerate for at least 1 hour to set.
Before serving, remove the cake from the refrigerator and slice it into 1-inch thick portions. Garnish each slice with chocolate shavings.