Method

1. Preheat the oven to 180°C/Gas 4. Grease and line a 20cm x 30cm Swiss roll tin with baking parchment.

2. In a small saucepan, mix together the cocoa powder and milk. Heat gently until the cocoa has dissolved and set aside until cooled.

3. In a large mixing bowl, whisk together the egg yolks and sugar until pale and fluffy. Whisk in the cooled chocolate milk.

4. Whisk the egg whites until stiff. Using a metal spoon, fold into the chocolate mixture

5. Turn the mixture into the lined tin. Bake for 20 minutes.

6. Turn the chocolate sponge out onto a large sheet of greaseproof paper. Cover with a damp, clean tea-towel and set aside to cool for 20 minutes.

7. Whisk the double cream until stiff. Stir in the yoghurt.

8. Spread the cream mixture over the chocolate sponge. Roll the sponge up over the filling to form a roulade. Decorate with strawberries and grated chocolate and serve.