Preheat the Oven: Preheat your oven to 200°F (95°C) and line two baking sheets with parchment paper.

Prepare the Meringue: In a clean bowl, use an electric mixer to beat the egg whites on medium speed until foamy. Add cream of tartar and continue beating until soft peaks form. Gradually add sugar, about one tablespoon at a time, beating at high speed until stiff, glossy peaks form. Mix in the vanilla extract and green gel food coloring until the desired shade is reached.

Pipe the Meringues: Transfer the meringue mixture into a piping bag fitted with a large star tip. Pipe the meringue onto the prepared baking sheets in a swirling motion to create a tree shape.

Add Decorations: Decorate each tree with assorted round sprinkles and top with a star sprinkle.

Bake: Bake in the preheated oven for 1.5 to 2 hours or until the meringues are dry to the touch and easily peel off the parchment paper. Turn off the oven and let the meringues cool completely inside to ensure they remain crispy.