For the grilled fruit
Preheat the oven to 130°C, gas mark 1.
To prepare the meringues, line two trays with baking paper or silicone baking mats.
Place the caster sugar in a microwave-safe bowl and microwave on high for 2 minutes or until hot to the touch.
Place the egg whites in the bowl of a stand mixer and whisk until soft peaks are formed.
Spoon the hot sugar into the egg whites as you whisk, beating for 7-8 minutes, until the mix is completely cold. The meringue should be very thick, glossy and form stiff peaks when the beater is lifted.
Lower the speed and add the muscovado sugar gradually. Beat until the sugar has dissolved completely.
Drop large spoonfuls of the meringue onto the prepared baking trays.
Bake for 2-2.5 hours, until the meringues are crisp but retain a marshmallow consistency on the inside.
To grill the fruit, prepare medium-hot coals. Place the fruit on the griddle and leave to form char lines. Allow to cool.
Whip the cream to soft peaks.
Serve the meringues with the fruit and top with the whipped cream.