Preheat your oven to 350°F (175°C). Line a 15x10-inch baking sheet with parchment paper and set aside.
In a large bowl, whisk eggs and granulated sugar together until the mixture becomes pale, thick, and slightly fluffy, about 3-4 minutes. You can use a hand or stand mixer for better aeration.
Sift the sifted flour and cocoa powder over the egg mixture and gently fold it in using a spatula, just until combined. Be careful not to deflate the batter—aim for a smooth, homogenous mixture.
Pour the batter into the prepared baking sheet, spreading it evenly with a spatula to fill all corners. Tap the sheet lightly on the counter to release any air bubbles.
Bake in the preheated oven for about 12-15 minutes, or until the cake springs back when lightly pressed. The sponge should be cooked through but still moist.
Once baked, remove the cake from the oven and immediately invert it onto a clean kitchen towel dusted with cocoa powder. Carefully peel off the parchment paper.
While the cake is still warm, spread ¼ cup of peanut butter evenly over the surface. Using the towel, gently roll up the cake from one short end, creating a tight spiral. Let it cool completely on a wire rack.
Meanwhile, prepare the chocolate ganache. Heat the heavy cream until just bubbling around the edges, then pour it over the chocolate chips and powdered sugar in a bowl. Let sit for 2 minutes, then whisk until smooth and glossy.
Unroll the cooled cake carefully. Spread the remaining peanut butter over the unrolled sponge, then re-roll it gently to form a spiral again. Place on a serving plate.
Pour the chocolate ganache over the top of the final rolled cake, allowing it to drip down the sides for a rustic look. Let the ganache set for about 15 minutes before slicing.
Slice into individual pieces, revealing the spiral of chocolate and peanut butter inside. Serve immediately or refrigerate for later enjoyment.
