1. Preheat your oven to 200°F (90°C) and line baking sheets with parchment paper.

2. In a clean metal or glass mixing bowl, beat the egg whites on medium speed until foamy.

3. Add cream of tartar and continue whipping. Gradually add granulated sugar one spoonful at a time.

4. Increase mixer speed to high and beat until stiff, glossy peaks form.

5. Gently fold in vanilla extract and optional gel food coloring.

6. Transfer mixture to a piping bag fitted with a large star tip.

7. Pipe tree shapes by stacking swirls from large to small.

8. Bake for 1.5 to 2 hours until dry to the touch.

9. Turn off oven and allow cookies to cool inside with the door slightly open for at least an hour.

10. Decorate with edible glitter or sprinkles, if desired.