Put the frozen berries in a saucepan with 25g (1oz) sugar. Heat gently until the fruit starts to steam then cover and simmer gently for 7-8 minutes until thawed and softened. Remove from the heat and leave to cool.

Pour 100ml (3 ½ fl.oz) hot water into a heatproof jug and stir in the Gelatine until thoroughly dissolved. Set aside to cool.

Make up the Egg White Powder according to the pack instructions (or use fresh egg whites) and whisk until stiff. Whisk in the remaining sugar to make a soft meringue.

Put the yogurt in a bowl and fold in the meringue, vanilla and the cooled Gelatine.

Spoon some of the yogurt meringue mixture into 4 x 300ml (½ pt) glass dishes or tumblers and pour over a little berry purée and swirl gently to give a rippled effect. Continue the layering until both mixtures are used up. Chill the mousses for at least 2 hours.

To serve, decorate the top of each mousse with fresh berries.