Nutrition per serving may change if servings are adjusted.
3 cups fat-free milk, divided
2 large eggs, separated
1/3 cup cornstarch
1 1/2 tablespoons vanilla extract
Yellow food coloring, (optional)
2/3 cup sugar
1/4 teaspoon cream of tartar
3 tablespoons water
Whisk together 1/4 cup milk, egg yolks and cornstarch in a large bowl. Heat remaining milk in a heavy saucepan until steaming. Gradually whisk milk into the egg mixture. Return to the saucepan; cook over medium heat, whisking constantly, until the custard boils and thickens, 1 to 2 minutes. Remove from the heat, stir in vanilla and about 3 drops yellow food coloring, if using. Transfer to a clean bowl and place a piece of wax paper or plastic wrap directly on the surface of the custard to prevent a skin from forming. Set aside to cool slightly.
Meanwhile, bring about 1 inch of water to a simmer in a saucepan. Combine egg whites, sugar, cream of tartar and water in a heatproof mixing bowl large enough to fit over the saucepan. Set the bowl over the barely simmering water and beat with an electric mixer at low speed, moving the beaters around the bowl constantly, until an instant-read thermometer registers 140 °F. (This will take 3 to 5 minutes.) Increase the mixer speed to high and continue beating over the heat for a full 3 1/2 minutes. Remove the bowl from the heat and beat the meringue until cool, about 4 minutes.
Whisk one-fourth of the meringue into the custard. Add the remaining whites and use a whisk to incorporate them with a folding motion.
Make Ahead Tip: Cover and refrigerate for up to 8 hours.