Preheat oven to 200°F and line two baking sheets with parchment paper.
In the bowl of a very clean and dry stand mixer fitted with a whisk attachment (or large bowl with a handheld mixer), combine egg whites, cream of tartar and salt, and whip on medium-high speed until combined and frothy and form soft peaks - about 30 to 60 seconds.
With the mixer running, add sugar 1 teaspoon at a time, mixing after each addition until the sugar has fully dissolved.
Continue to mix until the meringue holds stuff peaks and is glossy in appearance. This can take up to 10 minutes, so be patient!
Add vanilla extract and beat just to combine (about 10 seconds).
Transfer the meringue mixture to a clean piping bag fitted with a pastry tip (I like to use a French Star tip) and pipe into desired shape onto prepared baking sheets about 1" apart. They won't spread, but you still want to give them a little room.
Place on the middle rack of the oven and bake for 1 hour. Now turn off the oven - but don't open the door! Let them rest in the oven for another 1 hour while the oven naturally cools down.
Remove from the oven and let cool completely before transferring to an airtight container for storage. Enjoy!