Preheat oven to 275 degrees.
Line two baking sheets with parchment.
Use an electric mixer to whip egg whites and cream of tartar on low speed until foamy. This should take about 2 minutes.
Increase speed to medium and gradually add in sugar. Whip mixture to stiff peaks. This should take about 7-8 minutes. The egg whites should look soft and smooth.
Add vanilla and mix to combine.
Use a tablespoon to drop heaping 1/4 cup sized mounds of meringue onto the parchment paper on the baking sheets. Leave about 1 1/2 inches between each mound.
Place baking sheets in the oven and reduce the temperature to 225 degrees.
Bake until the meringues are firm and set for 1 hour and 15 minutes.
VERY IMPORTANT: Turn the oven off and leave the meringues to cool completely and continue drying. Do not open the oven. Leave them in the oven for 2 hours.
Remove the meringues from the parchment and place them on a baking sheet, serving tray or serving bowls.