Preheat your oven to 375°F (190°C) and grease a 15x10-inch jelly roll pan. Line it with parchment paper and lightly grease the paper.

In a large mixing bowl, beat the eggs and sugar together until light and fluffy. This might take about 5-7 minutes.

In a separate bowl, sift together the flour, cocoa powder, baking powder, and salt. Gradually fold this mixture into the egg mixture, being careful to maintain the fluffiness.

Spread the batter evenly in your prepared pan and bake for 12-15 minutes until set. A toothpick should come out clean.

Once baked, carefully turn the cake onto a clean kitchen towel dusted with powdered sugar. Peel off the parchment paper, roll the cake with the towel, and let it cool completely.

While the cake cools, beat the softened butter until creamy. Slowly add in powdered sugar and cocoa powder, followed by heavy cream and vanilla. Beat until fluffy.

Unroll the cooled cake gently, spread half of the buttercream over it, roll the cake back up, and use the rest of the buttercream to cover the surface of the rolled cake.

Use a fork to create bark-like patterns on the frosted cake. Top it off with powdered sugar and any desired decorations like chocolate shavings or fresh berries.

Slice, serve, and watch the smiles light up the room!