Preheat oven to 225 F.

Line two baking sheets with parchment paper.

Beat egg whites in the bowl of an electric mixer until frothy. Add cream of tartar. Beat until soft peaks form. Increase speed to medium-high.

Slowly add sugar, 1 tbsp at a time, until it is dissolved and stiff peaks form. Beat in vanilla extract.

Fill a piping bag with meringue, use a star tip. Pipe trees, starting from the middle, pipe a circle and then 2 more, finishing in the middle on top. Sprinkle with Christmas sprinkes.

Bake cookies for 1 1/2 to 2 hours. Check them often. Mine did get a little brown, which I should have prevented, but I was trying to multitask.

Turn the oven off, open its door and let them cool inside.

Store meringue cookies in an airtight container away from any heat or moisture