1. Preheat Oven and Prepare Pan:
- Preheat your oven to 375°F (190°C). Grease a 10×15-inch jelly roll pan and line it with parchment paper.
2. Make the Chocolate Cake:
- In a medium bowl, sift together the flour, cocoa powder, baking powder, and salt.
- In a large bowl, beat the eggs and sugar with an electric mixer until thick and pale, about 5 minutes. Add the vanilla extract.
- Gently fold the dry ingredients into the egg mixture until fully combined.
- Spread the batter evenly in the prepared pan and bake for 10-12 minutes, or until the cake springs back when lightly touched.
3. Roll the Cake:
- While the cake is still warm, turn it out onto a clean kitchen towel dusted generously with powdered sugar. Peel off the parchment paper.
- Starting from a short side, roll the cake tightly with the towel inside. Let it cool completely.
4. Make the Peanut Butter Filling:
- In a bowl, beat the peanut butter and softened butter until creamy. Gradually add powdered sugar, then mix in the heavy cream or milk one tablespoon at a time until the filling is smooth and spreadable.
5. Assemble the Buckeye Roll:
- Carefully unroll the cooled cake and spread the peanut butter filling evenly over the surface. Re-roll the cake (without the towel), placing it seam-side down on a serving platter.
6. Make the Chocolate Ganache (Optional):
- Heat the heavy cream in a small saucepan until it just begins to simmer. Pour it over the chocolate chips in a heatproof bowl. Let sit for 1 minute, then stir until smooth.
- Pour or drizzle the ganache over the rolled cake, letting it drip down the sides.
7. Chill and Serve:
- Refrigerate the Buckeye Roll for at least 1 hour to set. Slice and serve chilled or at room temperature.