Angel Cake

method:

• Preheat the oven to 160C/325F/Gas 3. Brush a 1.5 litre kugelhopf or ring tin with the oil and coat with flour, tapping out the excess. Mix together the caster sugar and sweetener.
• Whisk the egg whites in a thoroughly clean bowl until foamy. Add the cream of tartar and whisk again until stiff. Gradually whisk in the caster sugar and sweetener, a spoonful at a time. Stir in the milk powder and vanilla extract. Sift a thin layer of flour over the whisked mixture and fold in using a large metal spoon. Continue to sift and fold in the rest of the flour.
• Turn the mixture into the tin and level the surface. Bake for 20-25 minutes until firm to the touch. Loosen the edges of the mould with a knife and invert onto a wire rack. Leave to cool with the tin still in position. (If the cake has risen well above the top of the tin, cut a little off but bear in mind that the cake will shrink back as it cools.) Once cool, transfer to a plate.
• To make the frosting, beat the mascarpone in a bowl until softened. Add the cream, liqueur, lemon juice and sweetener and whisk until smooth. Using a palette knife, spread the cream mixture over the cake, swirling it decoratively with the tip of the knife. Scatter the fruits over the top of the cake to finish.