Preheat the oven to 350°F (177°C). Line a large baking sheet with parchment paper or a silicone baking mat. (Preliminary note: you will quickly reduce the oven to 200°F (93°C) in step 4.)

With a handheld mixer or a stand mixer fitted with a whisk attachment, beat the egg whites until soft peaks form, about 5 minutes. Add the sugar in 2 additions, beating for 30 seconds between, then continue beating on high speed until glossy stiff peaks form, about 2 more minutes. The peaks should be stiff enough that you can hold the whisk upright and the peaks won’t move. Add the vanilla extract and beat for 1 more minute. The peaks should still be very stiff. If not, keep on mixing on high speed. Using a rubber spatula, fold in the cream of tartar and cornstarch.

Spread the pavlova mixture into an 8-9-inch circle (see note for mini size). You can make decorative peaks with the back of a large spoon if desired. Make sure the edges are relatively tall and there is a nice dip in the center.

Place pavlova in the oven. As soon as you close the oven door, reduce heat to 200°F (93°C). The pavlova will stay in the oven as it cools down to 200°F (93°C). Bake until the pavlova is firm and dry, about 90 minutes total. Rotate the baking sheet if you notice some spots browning. Try to limit how many times you open the oven as the cool air will interrupt the baking.

Turn the oven off and let the pavlova cool inside the oven. Once the pavlova is cool, you can store it covered tightly at room temperature for up to 2 days. Or serve right away.

Once cool, top the pavlova with whipped cream and assorted toppings. Slice and serve.