Flourless Chocolate Cake

1: Preheat the oven to 175C.

2: Grease a 9-inch springform pan and dust with sugar.

3: Chop butter and chocolate into small cubes and microwave in 30-second intervals, stirring in between, until melted.

4: Allow to cool slightly and mix in the zest and juice of the orange.

5: Whisk in the egg yolks and set aside.

6: Beat the egg whites until stiff peaks form, gradually adding the sugar.

7: Mix a small amount of egg whites into the chocolate mixture to loosen it.

8: Gently fold the chocolate mixture into the egg whites.

9: Pour the mixture into the prepared pan and bake for 35-45 minutes.

10: Allow to cool, noting that it will collapse in the center.