Preparing the Cake

1. Preheat the Oven: Set your oven to 350°F (175°C) and line a jelly roll pan with parchment paper and lightly grease the sides.
2. Mix Dry Ingredients: In a bowl, combine the flour, cocoa powder, baking powder, and salt.
3. Combine Wet Ingredients: In a separate large bowl, whisk together the eggs, sugar, water, vegetable oil, and vanilla extract until smooth.
4. Combine Mixtures: Gradually add the dry ingredients to the wet ingredients, stirring until the batter is smooth and free of lumps.
5. Bake: Pour the batter into the prepared pan, spreading evenly. Bake for 12-15 minutes, or until the cake is set and a toothpick comes out clean.
6. Cool and Roll: Allow the cake to cool slightly, then invert onto a clean kitchen towel dusted with powdered sugar. Peel off the parchment paper, roll the cake with the towel from the short end, and let it cool completely.

Preparing the Filling

1. Mix Filling: Beat together peanut butter, powdered sugar, and heavy cream until smooth and fluffy.
2. Unroll and Fill: Carefully unroll the cooled cake, spread the filling evenly over the cake, leaving a small margin at the edges to prevent spilling.
3. Re-roll: Roll the cake back up, wrap in plastic wrap, and chill in the fridge for at least an hour to set.

Garnishing and Serving

1. Garnish: After the cake has chilled, sprinkle the top with mini chocolate chips, pressing them lightly to adhere.
2. Slice and Serve: Cut the cake into slices and serve chilled or at room temperature.