Preheat your oven to 200°F (93°C) and line a baking sheet with parchment paper. Ensure your mixing bowl and utensils are completely clean and dry.

In a clean, dry bowl, begin beating the egg whites on medium speed until they turn frothy, about 1-2 minutes.

Add the cream of tartar and beat until soft peaks begin to form, approximately 2-3 minutes.

Gradually add the granulated sugar, one spoonful at a time, while mixing on high speed. Beat for 5-7 minutes until stiff peaks form and the meringue is glossy.

Gently fold in the vanilla extract using a rubber spatula.

Transfer the meringue into a piping bag fitted with a star tip. Pipe a generous amount of meringue onto each sugar cookie base, forming a whimsical tree shape.

Bake for 1.5 to 2 hours until firm and completely dry. Keep an eye on them to prevent browning. After baking, turn off the oven and let the cookies cool inside.