Set oven to 130 degrees Celsius (Gas Mark 1). Line a large baking tray with baking parchment
Using a pencil, draw a 30-35cm circle onto the paper, using a plate or bowl as a guide. Then use a smaller bowl/plate as a guide and draw another circle inside the large circle to form a ring. You want the meringue wreath to have a hole in the centre of approximately 10cm diameter.
Put the egg whites in a super clean bowl and beat either with a hand beater or food mixer, using the whisk attachment to reach stiff peaks
Gradually add the caster sugar a tablespoon at a time and keep beating until the meringue is glossy.
Add the vanilla, cornflour and vinegar. Beat to mix.
Turn off the mixer and remove the bowl.
Spoon the meringue onto the prepared tray into a ring between the circles you have previously drawn
Using the back of the spoon, form a channel in the meringue all the way around. This will help hold the cream when you decorate it.
Place the wreath into the oven and cook for 1 hour.
Turn off the oven and leave the wreath in there until the oven is cool.
Whip the cream with the second measure of sugar and vanilla to soft peaks
Pile on top of the wreath and garnish with berries. Dust with Icing sugar and serve.