Preheat oven to 350°F (175°C). Line a 10×15-inch jelly roll pan with parchment, leaving some overhang, and lightly grease it.

Whisk flour, cocoa powder, baking powder, and salt in a bowl. In another bowl, beat eggs and sugar on high for 4–5 minutes until pale and thick. Stir in oil, vanilla, and milk. Gently fold in dry ingredients to keep the batter light, then spread evenly in the pan.

Bake for 12–15 minutes until the cake springs back when lightly touched. Remove from the oven and roll while still warm.

Dust a clean kitchen towel with powdered sugar, invert the cake onto it, and peel off the parchment. Starting from the short end, roll the cake with the towel into a spiral. Let cool completely for 20–30 minutes.

Beat peanut butter, cream cheese, and powdered sugar until smooth, then add vanilla. Fold in whipped cream until fluffy and chill for 10 minutes.

Unroll the cooled sponge, spread the filling evenly, leaving a ½-inch border, then roll it up again without the towel. Wrap in plastic wrap and refrigerate for at least 30 minutes.

Heat heavy cream in a small saucepan until it begins to simmer. Pour over chocolate chips in a heatproof bowl, let sit for 1 minute, then stir until smooth. Add butter for shine and let cool until thick but pourable.

Set the chilled cake on a wire rack over a tray and pour the ganache over it, letting it drip down the sides. Top with chopped peanuts, chocolate curls, or caramel. Refrigerate for 20 minutes to set before slicing.