Sprinkle gelatin over the cold water in a small cup and set aside to soften.
Put all dry ingredients, sweetener, salt, cream of tartar, in mixer bowl.
Separate the egg white from the yolk and pour egg white into mixer bowl.
Add vanilla to mixer bowl. Whisk ingredients on low just to combine.
Heat 1/2 cup water to boiling and pour into a heat proof bowl or measuring cup and add soften gelatin. Stir for a few moment to dissolve.
Turn mixer on low and trickle about half the hot liquid down the inside edge of the bowl, so as to not coagulate the egg. Turn the mixer on high and continue trickling the rest of the liquid into the mixer.
Allow mixture to continue on high for 7 minutes or until stiff peaks will form in the frosting.
Frost or pipe onto cooled baked goods immediately.