For meringue

1. Heat the oven to 120C. Use an electric hand-held mixer to beat the egg whites and salt until they form soft peaks. Add the sugar, a spoonful at a time, beating until just combined.  Once the sugar has been added, continue beating for two minutes until the mixture is thick and glossy. Using two teaspoons, spoon the mixture on to two trays lined with baking paper. Place in the oven and reduce the heat immediately to 100C, and bake for one hour and 15 minutes or until crisp underneath. Turn off the oven and leave to cool in the oven for three hours. Store in an airtight container for up to three weeks. 

For Eton mess

1. Hull the strawberries and cut in half or quarters if large. Toss with one tablespoon of liqueur and one tablespoon of icing sugar and set aside for 30 minutes.

2. Whiz half the raspberries to a puree with one tablespoon of icing sugar and remaining liqueur.

3. Whip the cream lightly until just firm, fold in the yoghurt, and chill.

4. To serve, roughly crush the meringue, and layer it in dessert glasses or jars with the cream, strawberries and remaining raspberries. Drizzle with the berry puree, dust with icing sugar and serve.