Heat the oven to 140C/fan120C/gas 1. Line two baking sheets with baking parchment or non-stick sheets. Whisk the egg whites and a generous touch of pink colouring (it will go very pale as it whisks) with an electric hand whisk, until stiff. Continue whisking as you sprinkle in the sugar, a tablespoon at a time, then whisk until the mixture is thick and glossy, and stiff peaks form as the whisks are removed from the mixture.
Using two tablespoons, make 18 large ‘quenelle’ shapes, spaced well apart on the baking sheets. Bake for about 11⁄2 hrs until they are crisp and will peel easily from the lining. Leave to cool in the oven for 30 mins with the door slightly ajar. They will keep in an airtight tin for up to a week.
When ready to serve, beat the mascarpone until smooth. Pour in the cream, add the sugar and whisk again to soft peaks. Very lightly stir in the fruit so it is rippled through the cream. Sandwich the meringues together with fruit cream. Pile onto a plate and eat the day they are made.