Black Forest Swiss Roll

1️⃣ Make the Sponge Cake

1. Preheat your oven to 180°C (350°F) and line a 30×40 cm (12×16 inch) baking tray with parchment paper.
2. Separate the egg whites from the yolks. Beat the egg yolks with sugar until pale and fluffy.
3. Mix in the flour, cocoa powder, and optional vanilla extract.
4. Whip the egg whites with a pinch of salt until stiff peaks form, then gently fold into the batter, keeping the mixture airy.
5. Spread the batter evenly onto the prepared tray and bake for 10–12 minutes, until set and lightly springy to the touch.

2️⃣ Roll the Sponge Cake

1. Turn the hot sponge cake out onto a clean, slightly damp kitchen towel or parchment dusted with sugar.
2. Roll the cake up immediately with the towel to prevent cracking. Let it cool slightly while rolled up.

3️⃣ Make the Whipped Cream

1. Whip the very cold cream with powdered sugar (and stabilizer if using) until firm and fluffy.

4️⃣ Assemble the Swiss Roll