Preheat the Oven: Preheat your oven to 200°F (93°C). Line a baking sheet with parchment paper.
Whip the Egg Whites: In a clean, dry mixing bowl, beat the egg whites on medium speed until foamy. Add the cream of tartar and continue beating until soft peaks form.
Add Sugar: Gradually add the granulated sugar, about 1 tablespoon at a time, while continuing to beat on high speed. Continue beating until stiff, glossy peaks form, and the sugar is fully dissolved.
Add Vanilla: Gently fold in the vanilla extract.
Shape the Meringue Trees: Transfer the meringue mixture into a piping bag fitted with a star tip. Pipe the meringue onto the parchment paper in a tree shape, starting from the base and working your way up. You can make small, stacked tree shapes, or pipe one large tree on each cookie base.
Bake: Bake the meringue trees in the preheated oven for 1.5 to 2 hours, or until the meringues are dry, crisp on the outside, and easily lift off the parchment paper. The meringues should be completely dry on the inside.
Cool Completely: Allow the meringues to cool completely on the baking sheet.
Decorate (Optional): If desired, decorate the meringue trees with sprinkles, edible glitter, or tiny colorful candies to add a festive touch.
Assemble: Place each meringue tree on a sugar cookie base for added stability and a fun, decorative touch.