Pavlova:
Preheat oven at 225˚ F.
Place parchment paper on a baking sheet, and trace 2 (6 to 8 inch circles).
Using a stand mixer, beat the egg whites until soft peaks form. Gradually add the sugar while continuing to whisk for 8 to 10 minutes, until the egg whites are stiff and the mixture is smooth and glossy. In a small bowl, combine the cornstarch, vinegar, and vanilla. Gently fold this mixture into the meringue, being careful not to overmix, just a quick 5 to 6 seconds should do.
Next, flip the parchment paper over so that the traced circles are facing down on the sheet pan. Spoon or pipe the meringue into the center of each circle, then use a spoon to spread it out and create a well in the center for the filling. Bake for 1 hour and 30 minutes. After baking, turn off the oven, but don’t open the door. Let the meringues sit in the oven for 2 to 3 hours (or up to 8 hours if you want a crispier shell). This step is crucial (don’t skip it)!
The outside of the meringue should be dry and crisp, while the inside will remain marshmallow-soft.
When you’re ready to serve, top one shell with whipped cream, then stack the second shell on top. Finish with the remaining whipped cream and macerated berries. Enjoy!
Whipped Cream:
Place the bowl of a stand mixer or a large mixing bowl into the freezer to chill for at least 10 minutes. Add heavy whipping cream, sugar, and vanilla to the chilled bowl. Use the wire whisk attachment on a stand mixer or a hand-held mixer to beat the ingredients together. Start on low speed, then gradually increase to high as the mixture begins to firm up. Beat for 60 to 90 seconds until stiff peaks form. Stopping once halfway through to scrape down the sides of the bowl.
Use immediately or cover tightly and chill in the refrigerator for up to 2 hours. If stored overnight, the cream will have to be re-whipped before serving.
Macerated Berries:
Combine berries with sugar and juice in a large bowl until sugar begins to dissolve.
Let the mixture sit at room temperature, tossing occasionally, until berries are juicy, 1 to 2 hours.