1

Preheat the oven to 180°C, fan 160°C, gas mark 4. Line a 20cm x 30cm swiss roll tin with baking paper.

2

In a large mixing bowl, whisk the egg whites until foamy, then add the cream of tartar with a pinch of salt and continue to whisk until the mixture is stiff and forms peaks that hold their shape when the beaters are removed.

3

Sift the flour, 2 tablespoons cocoa and sugar over the egg white mixture, then gently fold until smooth and combined.

4

Spoon the batter into the prepared tin and smooth the surface with a spatula. Bake for 12-15 minutes or until the sponge feels firm and springy to the touch.

5

Lightly dust a sheet of baking paper with 1 teaspoon cocoa powder. Turn the cake out onto the baking paper, discarding the sheet from the tin, then roll up the roulade from one short side, with the cocoa-dusted paper inside as you roll. Set aside to cool.

6

Put the coffee granules in a mixing bowl, add 1 teaspoon boiling water and stir to dissolve. Add the icing sugar and quark, and mix until smooth and combined.

7

Unroll the sponge and drizzle over the Marsala wine, then spread over the quark mixture. Scatter over half of the grated chocolate and re-roll the sponge without the paper. Scatter the remaining chocolate over the top of the roulade and cut into slices to serve.