First, make the meringues. Preheat the oven to 200° and have ready a parchment-lined baking sheet.

In a medium bowl, add the cold egg white and cream of tartar. Beat with an electric mixer until foamy and soft peaks start to form. Then, slowly stream in the granulated sugar while continuing to beat on medium speed. When it has stiff peaks, stop mixing. At this point, you can scrape it into a piping bag. If you’re not using a piping bag, have two spoons ready. Use two spoons (or the piping bag) to make four circles of meringue on the baking sheet. Use a spoon to make a slight divot in each circle to hold the fillings later.

Bake for 45 minutes, and then turn off oven and let cool for 1 hour. Do not open the oven during the cooling process. The meringues should not appear sticky to the touch, though the insides may be.

After cooling the meringues, move them to serving platter. Make the whipped cream by beating together the heavy cream and powdered sugar. Add a splash of vanilla when the cream has soft peaks. Divide the whipped cream between the meringue shells. Top with the mixed berries and serve.