Preheat oven to 225°F.

In a mixing bowl, beat the egg whites, salt, and cream of tartar until stiff peaks form.

While continuing to mix, slowly add sugar until dissolved and mixture is thick with stiff peaks.

Mix in vanilla extract and 4 drops of green food coloring.

Line baking sheets with parchment paper or a silicone baking mat.

Using a star tip, pipe circles to make wreaths.

Pipe in a swirling circular motion to make trees, starting with a larger circle on the bottom and progressively smaller circles on top.

Add sprinkles and bake for 45 minutes.

Turn off oven and leave them undisturbed for 1 hour.

Remove from oven and let cool completely.

Store in a dry, airtight container.