- Preheat oven to 250 degrees F. Line a baking sheet with parchment paper. Create a template for your wreath-shaped pavlova by drawing a 9" circle on the paper. Inside this circle, draw a 4" circle.
- Beat egg whites and cream of tartar with an electric mixer until very soft peaks form. Gradually add the berry sugar, beating constantly, until all is incorporated. Keep beating until mixture is thick, glossy and stiff peaks form. Now beat in the cornstarch and vanilla.
- Spoon large, equal dollops of the meringue mixture inside the borders you've drawn on the paper, creating a wreath shape. With a thin spatula, smooth the edges of the wreath.
- Bake 90 minutes, and then turn off the heat and leave the meringue in the oven to cool and dry 3 hours and then remove from oven. (The meringue can be made up to a day in advance. Store in an airtight container until ready to serve.)
- Whip the cream until soft peaks form. Now sweeten with 3 Tbsp. icing sugar and beat until stiff peaks form. Pipe or spread whipped cream on top of the meringue.
- Decorate the top of the pavlova with the fruit. Garnish with mint, dust with icing sugar, if using, and serve.
Note: Berry sugar is very finely granulated sugar that's sold in small bags. It can be found in the aisle where other sugar products are sold.