Preheat your oven to 200 and line two baking sheets with parchment paper. Prep a piping bag with your desired tip.
In a stand mixer with whisk attachment, whip the egg whites and vanilla on low until they are frothy. Add the cream of tartar and salt with the mixer running and whip 10-20 seconds until mixed well.
Keep the mixer going on low and slowly add 1/4 cup of the sugar. Increase to medium speed and continue slowly adding the rest of the sugar. Continue mixing on medium until the eggs are glossy and stiff and hold a stiff peak when you dip the whisk into them and turn upright. It is ok if the meringue goes from 12 to 11 on the clock when you flip it over, but if it droops more than that, whip further. I whipped mine for about 11 minutes. You can turn the mixer to high and finish this faster, but meringue whipped at a slower rate will be more stable and hold up better to mixing in flavorings and piping.
Transfer the mixture to the piping bag and pipe quarter sized (or your preferred size) meringues. They will not spread so they can be close together. Make sure both oven racks are near the center and place the two sheets of meringues into the oven. Bake for 2 hours without opening the door.
After 2 hours, turn the oven off and crack the door with a wooden spoon and let cool slowly for 30 minutes in the oven. This prevents them cracking. After 30 minutes, open the oven door and let them cool another 20-30. Then cool fully on the counter before storing. They should be stored at room temp or frozen. Do not store in the fridge as they will get damp and soft. If frozen, defrost at room temp when ready to eat.