Meringue Squares

Ingredients:
6 egg whites
½ tsp salt
250g caster sugar, plus 2 teaspoons
½ tsp cream of tartar
1 tsp vanilla extract
butter for greasing
250ml double cream
4 passionfruit
175g blackberries
175g strawberries, quartered

Method:

1. Preheat the oven to 220°C. 
2. In a large bowl, whisk the egg whites and salt until peaks begin to form. 
3. Gradually add the 250g of sugar, then the cream of tartar and vanilla, whisking all the while at speed, until the whites are stiff and glossy. 
4. Butter a swiss roll tin then spread evenly with the meringue mixture. 
5. Put in the oven, close the door, then immediately switch off the oven and leave overnight, without opening the door. 
6. When you want to serve it, remove to a large plate. 
7. Whisk the double cream until thick but still soft and spread over the marshmallow meringue. 
8. Scoop out the seeds and pulp of the passionfruit and dot them over the cream. Tumble the blackberries over the top. Toss the quartered strawberries in the remaining 2 teaspoons of caster sugar and arrange them on the cream, too. 
9. Cut into squares.