Preheat your oven to 350°F (175°C). Grease and line a 10×15-inch baking sheet with parchment paper.

1. In a medium bowl, whisk together the flour, cocoa powder, baking powder, and salt. Set aside.
2. In a separate bowl, beat the eggs and granulated sugar with an electric mixer on high speed until pale and fluffy, about 5 minutes. Add in the vanilla extract and mix.
3. Gradually fold the dry ingredients into the egg mixture, being careful not to deflate the batter. Add the melted butter and mix gently.
4. Pour the batter onto the prepared baking sheet and spread it evenly with a spatula.
5. Bake for 10-12 minutes, or until the cake springs back when lightly touched.
6. While the cake is baking, prepare a clean kitchen towel by dusting it with powdered sugar.
7. Once the cake is done, remove it from the oven and turn it out onto the prepared towel. Peel off the parchment paper.
8. Carefully roll the cake, starting from one short end, with the towel inside. Let the cake cool completely while rolled up.
9. In a separate bowl, whip the heavy cream with powdered sugar and vanilla extract until stiff peaks form.
10. Once the cake has cooled, unroll it carefully. Spread the whipped cream evenly over the surface of the cake, leaving a small border around the edges.
11. Re-roll the cake, this time without the towel, and place it seam-side down on a serving platter.
12. Chill the Swiss roll in the refrigerator for at least 1 hour before slicing.