Light, fluffy marshmallows which pack a real plum punch - cut into chunky cubes and dust with icing sugar, or dip in a chocolate fondue.
Put the plums in a saucepan with 50g of sugar. Cover with a lid and cook over low heat, stirring occasionally, until really soft and mushy – this will take about 20 mins. Whizz in a blender or food processor to a smooth purée.
Line a 20cm square tin with baking parchment. Sift the icing sugar and cornflour together, and sprinkle a little over the base of the tin. Put the gelatine leaves, one by one, in a bowl of cold water to soften.
Put the remaining sugar in a saucepan with 200ml water. Heat gently until the sugar has dissolved, then increase the heat, add a sugar thermometer, and boil until it reaches 125C.
As the sugar nears the correct temperature, beat the egg whites in your largest bowl with an electric whisk until stiff peaks form. When the sugar syrup is ready, stir in the plum purée, then squeeze out the excess water from the gelatine leaves and stir these in too until completely melted. With your whisks running, gradually pour the plum-sugar syrup onto the egg whites and beat in. Once you’ve added all the syrup, keep beating the mixture until nice and thick. Pour into the prepared tin and leave at room temperature to set for a few hrs.
When set, dust another sheet of parchment with some more of the cornflour-icing mixture and turn the marshmallows out onto it. Using a big sharp knife, dipped in more of the dusting mix, cut the marshmallows into chunky squares, then toss with more of the dusting mix to coat all over.