Preheat your oven to 250°F (120°C). Line a baking sheet with parchment paper and set aside.
In a clean, dry mixing bowl, beat the egg whites on medium speed until soft peaks form.
Gradually add the granulated sugar, a tablespoon at a time, while continuing to beat the egg whites. Beat until stiff, glossy peaks form.
Sprinkle the cornstarch over the meringue and gently fold it in, followed by the white vinegar and vanilla extract. Be careful not to deflate the meringue.
Spoon the meringue mixture onto the prepared baking sheet, forming 6 small nests with indentations in the center for the filling.
Bake the mini pavlovas in the preheated oven for 1 hour, or until they are crisp and dry on the outside. The insides should remain soft and marshmallow-like.
Once baked, turn off the oven and let the mini pavlovas cool completely with the oven door slightly ajar.
While the pavlovas are cooling, prepare the topping. In a mixing bowl, beat the chilled heavy cream and powdered sugar until stiff peaks form.
Spoon a dollop of whipped cream into the center of each cooled mini pavlova.
Top the whipped cream with fresh berries and garnish with mint leaves, if desired.
Serve and enjoy these delightful mini egg pavlovas as a light and elegant dessert that's perfect for any occasion!