Preheat oven to 375°F (190°C). Grease a 15x10x1-inch jelly roll pan, line with parchment paper, then grease the parchment paper.

In a medium bowl, whisk together the flour, cocoa powder, baking powder, baking soda, and salt.

In a large bowl, beat the egg yolks until light and pale. Gradually beat in the granulated sugar, followed by the oil, buttermilk, and vanilla extract.

Gradually add the dry ingredients to the wet ingredients, mixing on low speed until just combined.

In a separate, clean bowl, beat the egg whites on high speed until stiff peaks form.

Gently fold the whipped egg whites into the chocolate batter in two or three additions.

Pour batter into the prepared pan and spread evenly. Bake for 12-15 minutes, or until the top springs back when lightly touched.

Lay a clean kitchen towel on the counter and dust generously with confectioners' sugar. Immediately invert the hot cake onto the towel. Peel off the parchment paper. Starting from a short end, roll the warm cake up with the towel inside. Let it cool completely on a wire rack.

In a large bowl, beat the softened butter and creamy peanut butter until smooth.

Beat in the powdered sugar until fully incorporated, then mix in the vanilla extract.

In a separate bowl, whip the heavy cream to stiff peaks. Gently fold the whipped cream into the peanut butter mixture until light and fluffy.

Once the cake is completely cool, gently unroll it. Spread the peanut butter filling evenly over the cake, leaving a small border around the edges.

Carefully reroll the cake (without the towel).

Wrap the cake roll tightly in plastic wrap and refrigerate for at least 2 hours to set before slicing and serving.