Add ice water to the flour mixture, 1 Tbsp at a time, mixing after each addition. Continue adding ice water just until the dough comes together (I used all 5 Tbsp).
With a hand mixer or standing mixer (using the whisk attachment) on medium-low speed, whip the egg whites, cream of tartar, and vanilla extract together until the mixture is foamy.
Add sugar, 1 Tbsp at a time, to the egg whites, whipping after each addition. Then, continue whipping the mixture on med-high speed until the sugar has dissolved and the egg whites are smooth, glossy, and have formed stiff peaks (about 2-4 minutes).
*Separate the egg yolks and egg whites while the eggs are still cold--they separate easier this way. I separate the eggs while the pie crust is baking in the oven.
*Let the egg whites sit for 30 minutes before whipping to stiff peaks for meringue--the egg whites will whip faster when the egg whites are at room temperature.
*Finally, the filling calls for 4 egg yolks and the meringue calls for 6 egg whites. You will have 2 extra yolks you do not use for this recipe. If desired, you can make the meringue with 4 egg whites. Reduce the sugar to 4 Tbsp and the vanilla extract to 1/2 tsp. The meringue will not be as tall as how it's photographed if you reduce the egg whites.