Pre-heat your oven to 200℉ and line one large (or 2 small) baking sheets with parchment paper.
You can make these in either a stand mixer or with a hand mixer. Either way, add your egg whites, cream of tartar, and salt to the bowl.
Begin to mix at medium speed just until the egg whites get foamy.
While continuing to whisk, slowly pour in the sugar. Keep mixing for about 5 more minutes or until the egg whites form stiff peaks. You should be able to hold a scoop of the mixture upside down and have it keep it's shape and not drip. It will also be nice and shiny.
If you do not have a piping bag, you can just spoon dollops (about 2 tablespoons) to the prepared baking sheet. They will look more rustic but taste just as amazing!If you want to use a piping bag/star tip, fill your bag, and pipe swirls onto the prepared baking sheet. These will not spread in the oven so you don't need to worry about leaving a ton of space between them. About 1" is enough.
Bake in the oven for 1 hour then turn off the oven and leave them in the oven for 1 more hour. Do not open the door during this time!