Preheat oven to 350°F (175°C). Grease a 10x15 inch jelly roll pan and line with parchment paper.
In a bowl, whisk together flour, cocoa powder, baking powder, and salt.
In another bowl, beat eggs and granulated sugar until thick and pale. Add vanilla extract.
Gradually fold in the dry ingredients until just combined.
Spread the batter evenly in the prepared pan. Bake for 10-12 minutes.
While the cake is baking, prepare a clean kitchen towel dusted with powdered sugar.
Once the cake is done, immediately turn it out onto the towel and peel off the parchment paper. Roll the cake up with the towel and let it cool completely.
In a bowl, whip the heavy cream and powdered sugar until stiff peaks form.
Unroll the cooled cake, spread the whipped cream evenly, and sprinkle chocolate chips if using. Roll the cake back up without the towel.
Chill in the refrigerator for at least 1 hour before serving.