- With the rack in the middle position, preheat the oven to 200°F (100°C). Line a baking sheet with parchment paper.
- In a small bowl, dissolve the cornstarch in the vinegar. Set aside.
- In a bowl, beat the egg whites with an electric mixer until frothy. Gradually add the sugar, beating until stiff peaks form. Gently stir in the cornstarch mixture.
- With a ¼-cup (60 ml) ice cream scoop, form 6 round meringues and place them on the prepared sheet, spacing them evenly. With the back of a spoon, make a shallow well in the centre of each meringue.
- Bake for about 2 hours or until the meringue nests are dry and easily peel off the paper. Turn off the oven, and let them dry for about 2 hours, leaving the oven door slightly ajar, using a wooden spoon. Let cool on the baking sheets.
- When ready to serve, combine the berries with the sugar in a bowl.
- Spoon the double cream into the centre of each meringue nest. Top with the berries.
Double cream has a fat content of 48% and can be found in certain grocery stores or gourmet markets. If unavailable, you may replace the double cream with whipped cream or Greek yogurt.