Perfect for topping a lemon pie.

4 large egg whites, room temperature
1 cup granulated sugar
1 pinch cream of tartar
1/2 teaspoon pure vanilla extract

Combine egg whites, sugar and cream of tartar in a clean mixer bowl.
Place over a sauce pan half-full of simmering water.
Continuously whisk until sugar has fully dissolved and mixture has reached 160°F.
Place mixer bowl on stand mixer and whip on medium speed until stiff peaks form.
Add vanilla and combine.