Prep the cake sheet – Preheat oven to 350°F (175°C). Line a 12×17″ baking tray with parchment paper. In a bowl, mix cake flour, cocoa powder, and espresso powder.

Make the meringue – Separate egg whites and yolks. Beat egg whites with cream of tartar until frothy. Slowly add 100g sugar, beating until stiff peaks form.

Prepare the egg yolk batter – Beat egg yolks with the remaining 50g sugar. Mix in milk, oil, and vanilla extract. Sift in the dry ingredients and mix until just combined.

Combine batters – Gently fold 1/3 of the meringue into the yolk mixture. Add the rest and fold carefully until no streaks remain.

Bake the cake – Pour batter into the prepared tray, spreading evenly. Bake for 13-14 minutes until lightly browned. Let cool for 5 minutes, then flip onto parchment paper and carefully peel off the original lining.

Roll the cake – While warm, roll the cake with parchment paper from the short end. Let it cool completely.

Make the espresso whipped cream – Whip cream, powdered sugar, espresso powder, and vanilla to stiff peaks.

Assemble the roll cake – Unroll the cake and spread a thick layer of espresso whipped cream, leaving 2 inches at the end. Roll it back up and wrap in plastic wrap. Chill for at least 3 hours or overnight.

Serve – Trim the ends for a clean swirl. Slice into 1-1.5″ pieces and garnish with whipped cream and coffee beans if desired.