Preheat oven to 275. Line cookie sheets with parchment paper
In a stand mixer bowl combine egg whites, cream of tartar, salt and vanilla. Beat until they stand in soft peaks
Stir sugar and Starbucks Via Ready Brew together in a clean dry bowl.
Slowly add the sugar/Starbucks mixture to the egg mixture 1 spoonful at a time while continuing to beat the mixture.
Once everything is fully incorporated and the mixture forms stiff peaks shape the meringue on the parchment paper. You can pipe the mixture or use a spoon to drop it on the parchment.
Bake for 30 minutes then turn the oven off. Leave meringue cookies in the oven overnight or for a few hours to make sure they are fully dry.
Cool completely before storing
I use room temperature eggs when I make meringue cookies. Make sure you add the sugar to the mix slowly and give it time to incorporate before adding another spoonful. If you add to much the eggs will deflate and the cookies will not turn out correctly.