Preheat oven to 200 degrees F. Prepare a baking sheet by lining with a silpat or parchment paper.
Note - if you don't have super fine baking sugar, you can run it through your food processor for a minute or two to turn it into a finer grain.
In the bowl of a stand mixer using the whisk attachment, beat the egg whites on low-medium speed until foamy. Add the cream of tartar and continue to beat the whites until they hold soft peaks. Add the sugar, a little at a time, and continue to beat until the meringue holds very stiff peaks. When you think they're done, rub a small amount in between your fingers to ensure all the sugar has dissolved. Do not over process; you want them to have a nice sheen. Beat in the vanilla and peppermint extract. Add enough green gel food coloring to achieve desired color.
Use either a pastry bag fitted with a 1/2 inch star tip, or just a plastic storage bag with the corner snipped off. Transfer the meringue to the bag and, holding the bag vertically, pipe with even pressure little swirly mounds about 1-2 inches tall. Be aware that the larger and taller you make your meringues, the more likely they are to fall over during the drying process.
Bake the meringues for approximately 90 minutes or until they are dry and crisp to the touch. Turn off the oven, open the door, and leave the meringues in the oven to finish drying several hours, or even overnight.
Store in air tight container and they will keep several days at room temperature.
Makes 20-24 Meringue Ghosts.