Prepare the pan. Heat the oven to 350°F (175°C). Grease a 10x15 inch jelly roll pan, line it with parchment paper, and grease the parchment.

Whip the yolks. Beat the egg yolks with 1/2 cup of the sugar and the vanilla for 3 to 4 minutes, until pale and thick.

Combine the dry ingredients. Sift the flour, cocoa, baking powder, and salt together. Fold them into the yolk mixture. The batter will be thick.

Whip the whites. In a clean bowl, beat the egg whites until foamy. Add the remaining 1/4 cup sugar gradually and beat until stiff, glossy peaks form.

Fold. Stir a third of the whites into the batter to loosen it, then gently fold in the rest until no streaks remain. Do not stir hard, or you will lose the air.

Bake. Spread the batter evenly in the pan and bake for 10 to 12 minutes, until the cake springs back when touched lightly.

Roll while warm. Dust a clean kitchen towel generously with powdered sugar. Turn the hot cake out onto the towel, peel off the parchment, and roll the cake up with the towel, starting from a short end. Cool completely on a rack, about 1 hour.

Make the filling. Beat the cream cheese, peanut butter, powdered sugar, and vanilla until smooth. In another bowl, whip the cold cream to stiff peaks. Fold the whipped cream into the peanut butter mixture in two additions. Fold in the chopped peanut butter cups, if using.

Fill and re-roll. Gently unroll the cooled cake. Spread the filling evenly, leaving a 1 inch border. Roll the cake up again without the towel, ending seam side down.

Chill. Wrap the roll and refrigerate for at least 1 hour so it firms up and slices cleanly.

Add the ganache. Heat the cream until it just begins to steam, pour it over the chocolate chips, wait 2 minutes, and stir until smooth. Let it cool for 5 to 10 minutes, until it thickens slightly.

Decorate. Spoon or drizzle the ganache over the roll. Top with chopped peanut butter cups, a dusting of powdered sugar, and whipped cream if you like.