Soft meringue and berry roll

Preheat oven to 160 ºC. Lightly oil a 25 x 30 cm baking pan. Line with baking paper. Whisk egg whites to soft-peak stage. Continue whisking, adding castor sugar a little at a time, until mixture is thick and glossy. Stir in lemon juice and cornflour. Spread meringue evenly in baking pan, bake for 20 minutes and cool. Add berries to the mascarpone, stir until combined. Sprinkle a large piece of baking paper liberally with icing sugar. Turn meringue onto icing sugar and let cool completely. Spread chilled filling over meringue and roll up carefully. Use baking paper as guide. Place paper-wrapped roll on a large piece of plastic wrap and roll up well to secure. Refrigerate for six hours. Remove plastic and paper, cut into thick slices and serve with extra berries.
Serves 6.