Heat oven to 275 degrees fahrenheit.

Grease a pie plate and dust well with cornstarch, using a pastry brush to distribute evenly.

Combine sugar and 1 tablespoon cornstarch in bowl.

Using a handheld or stand mixer fitted with whisk attachment, whip egg whites and cream of tartar on low speed until foamy, about 1 minute. Increase speed to medium high and whip to soft, billowy mounds, about 1 to 3 minutes.

Gradually add sugar mixture and whip until glossy, stiff peaks, 3 to 5 minutes. Stiff peaks will stand straight up when you hold the whisk upright and do not flop over.

Add vanilla and whip until incorporated.

Spread meringue into prepared pie plate, following all the contours of the pie plate and over the edges.

Bake for 1 ½ hours. Rotate pie plate, reduce temperature to 200 degrees fahrenheit and bake until completely dried out, about 1 hour longer.

Let cool completely, about 30 minutes.