About the only way to make whipping up classic French meringue simpler--and safer--is by using meringue powder. Comprising mainly dried egg whites and confectioner's sugar, meringue powder has everything a classic meringue does, without the uncooked albumen. Dried egg whites undergo high-temperature processing that sterilizes them but doesn't cook them, eliminating the risk of salmonella while preserving their ability to form stiff peaks. Homemade meringue powder has a one to two-week shelf life, but you can increase it by storing it with a desiccant to absorb moisture and prevent clumping.
Sift 3 parts confectioner’s sugar into a mixing bowl followed by 1 part dried egg white powder. You need about 3/4 cup of confectioner's sugar and 1/4 cup of dried egg whites to make enough meringue powder for a standard 9-inch pie.
Add a pinch of cream of tartar and a pinch of cornstarch for each combined cup of sugar and egg whites. For example, if you used 3/4 cups of sugar and 1/4 cup of egg white powder, you would add 1 pinch each cream of tartar and cornstarch, or about 1/2 teaspoon of both.
Whisk the ingredients until combined. Sift all the ingredients into another mixing bowl and then back into the original mixing bowl two times. You must sift the meringue powder four times for uniform ingredient distribution.
Transfer the meringue powder to an airtight container. Insert a packet of food-grade ceramic desiccant or a ceramic desiccant disk in the meringue powder to increase its shelf life.
Store meringue powder in the refrigerator up to one month. If you see clumps develop, exchange the old desiccant for a new one. Sift the meringue powder once again before using it.
To whip up a meringue using meringue powder, add 2 parts cold water to a stand mixer and gradually sprinkle in 1 part meringue powder while operating the whisk attachment on high. Whip the meringue until it's dry and forms stiff peaks, about 5 minutes. You need about 1 cup of water and 1/2 cup of powder for 3 cups of meringue.
To make royal icing from meringue powder, whisk together 1 cup of confectioner's sugar, 1 1/2 tablespoons of warm water and 2 tablespoons of meringue powder on medium speed until it develops a creamy texture, about 6 to 7 minutes.