Preheat your oven to 200°F (93°C) and line two baking sheets with parchment paper.

In a clean, dry bowl, whisk the egg whites on medium speed until foamy. Add the cream of tartar and continue beating until soft peaks form.

Increase the speed to high and add the granulated sugar gradually, one tablespoon at a time. Continue to beat until the meringue is glossy and forms stiff peaks.

Add the vanilla extract and mix just until combined. If desired, add a few drops of green food coloring and gently mix for an even color.

Transfer the meringue into a piping bag fitted with a large star tip. Pipe the meringue onto the prepared baking sheets, starting from a small base and swirling upward to create tree shapes.

Bake the meringues in the preheated oven for 1.5 to 2 hours, or until they are dry and can be easily lifted from the parchment paper. Turn off the oven and let the meringues cool completely in the oven with the door slightly ajar.

Once cooled, optionally dust with edible glitter or sprinkles for a festive touch.