Preheat oven to 350°F and line a baking sheet with parchment paper. Set aside.

In a large mixing bowl, use an electric mixer with a whisk attachment to whip the egg whites until foamy. Add in the cream of tartar and cornstarch and mix thoroughly.

Slowly add in the granulated sugar a little bit at a time, letting the mixer run in between additions. Use a spatula to scrape the sides of the bowl if any sugar gets stuck there.

Continue whipping the egg whites until it becomes stiff peaks.

Use a spatula to plop down six mounds of meringue onto your lined baking sheet. Shape the meringue into round shapes.

Place the baking sheet into the oven and turn the heat down to 250°F. Bake for 1 hour or until the surfaces are dry and hard.

Turn off the oven and keep the oven door closed. Leave the pavlovas inside to cool for at least 1 hour or overnight.

In a small pan, bring blackberries, lemon juice, and water to a boil. Muddle the blackberries until it reduces into a jammy consistency, about 5-7 minutes.

Push the blackberry sauce through a fine mesh sieve into a small bowl to remove the seeds. Discard the seeds and set the sauce aside.

In another mixing bowl, whip together whipping cream, powdered sugar, and vanilla extract until it thickens.

When the pavlovas have cooled, use a spoon to crack open a hole on top of each pavlova. Spoon in whipped cream and top with a teaspoon of blackberry sauce.

Garnish with fresh blackberries.