Preheat the oven to 225°F (110°C) and line a baking sheet with parchment paper.

In a clean, dry bowl, beat the egg whites at medium speed until foamy. Add cream of tartar and continue beating until soft peaks form.

Gradually add sugar, one tablespoon at a time, beating on high until stiff, glossy peaks form. Gently fold in the vanilla.

Transfer the meringue to a piping bag with a round tip and pipe ghost shapes onto the baking sheet. Place two mini chocolate chips on each ghost for eyes.

Bake for 1½ to 2 hours, until dry and crisp. Turn off the oven and let the meringues cool completely inside before removing.