Preheat your oven to 225°F and line a baking sheet with parchment paper. Draw a 9-inch circle on the parchment as your meringue guide. Having this circle marked out saves you from eyeballing it and ending up with an oddly shaped base.

Pour those 4 egg whites into a super clean, dry bowl—seriously, any grease will mess everything up. Add the cream of tartar and beat on medium-high speed until soft peaks form and the mixture looks foamy, about 2 minutes. You'll know you're there when the peaks droop slightly when you lift the beaters.

Gradually sprinkle in your 1 cup granulated sugar while beating constantly, adding a couple tablespoons at a time. Keep going until stiff, glossy peaks form and the mixture feels smooth, not grainy—this takes about 5-7 minutes total. Don't panic if it takes longer; every mixer's different.

Gently fold in the cornstarch, white vinegar, and vanilla extract using a spatula. I fold about 20 times until barely combined—overmixing collapses all those air bubbles you just whipped in. Scoop the meringue onto your parchment circle and spread it into a shallow bowl shape with slightly higher edges.

Bake at 225°F for exactly 1 hour and 15 minutes, then turn off the oven and crack the door open about 2 inches. Let it cool completely inside the oven for another 30 minutes—this gradual cooling prevents cracking. Mine always sticks a tiny bit to the parchment, and that's totally fine.

Remove the pavlova from the oven and let it cool to room temperature on the counter. Whip your 2 cups heavy cream with 2 tbsp powdered sugar until soft peaks form—just a couple minutes. Spread or dollop the cream all over your meringue base right before serving.

Top generously with your 1 cup sliced strawberries and 1 cup blueberries, adding them just 10-15 minutes before people eat. Adding the berries too early makes everything get weepy, so timing this right keeps your strawberry blueberry pavlova cozy looking gorgeous.