To a medium saucepan set over medium-high heat, add sugar and water. Cook, stirring only until the sugar dissolves. Do not stir once mixture comes to a boil. Cook mixture until it reaches 240°F.
Meanwhile. To the bowl of a stand mixer fitted with a whisk attachment, add whites. Mix over low speed until whites are frothy. Add cream of tartar. When sugar solution reaches 200°F, increase mixer speed to medium and continue whipping.
When sugar mixture reaches 240°F, slowly drizzle the mixture into the whipping egg whites. When all sugar has been added, increase the mixer speed to medium-high and whip until stiff, shiny peaks form. Use as desired.
