1. Preheat the oven to 350°F and line a 10×15-inch jelly roll pan with parchment paper. Lightly grease the parchment.

2. Beat the eggs and granulated sugar until thick, pale, and airy.

3. Sift the flour, cocoa powder, baking powder, and salt together, then gently fold them into the egg mixture. Stir in the vanilla.

4. Spread the batter evenly into the prepared pan and bake for 10 to 12 minutes, until the sponge springs back lightly.

5. Dust a clean kitchen towel with powdered sugar, turn the warm cake onto it, peel off the parchment, and roll the cake up with the towel. Let it cool completely.

6. Melt 6 ounces of white chocolate and let it cool slightly. Beat cream cheese, powdered sugar, and vanilla until smooth, then mix in the cooled white chocolate.

7. Whip the heavy cream to soft peaks and fold it into the white chocolate cream cheese mixture.

8. Carefully unroll the cooled cake. Spread raspberry preserves over the sponge, then spread the filling on top and scatter with raspberries.

9. Roll the cake back up gently, wrap it, and chill for at least 1 hour.

10. Melt the remaining 4 ounces white chocolate with butter and a splash of cream until smooth. Spread it over the chilled roll.

11. Use a fork to make bark-like ridges, then decorate with raspberries, citrus zest, and powdered sugar.

12. Chill until set, then slice with a warm clean knife and serve.