These friendly little ghosts get a dose of “slime” with the help of some bright green matcha. Matcha comes in various forms and grades, the main two being ceremonial (a higher grade of tea with a softer, more subtle matcha flavor) and culinary (made from slightly lower quality tea with a bolder matcha punch). You'll use ceremonial grade for this recipe since it pairs nicely with the homemade meringue.
Preheat the oven to 250˚ F. Line two baking sheets with parchment paper. Beat the egg whites and salt in a large bowl with a mixer on medium speed until frothy. Add the cream of tartar and increase the speed to medium high; beat in the sugar 1 tablespoon at a time, then beat in the vanilla. Continue beating until the meringue is thick, glossy and holds stiff peaks, about 6 more minutes.
Transfer the meringue to a large piping bag fitted with a large round tip. Pipe into spiral cone shapes, 2 inches in diameter and 3 inches tall, about 2 inches apart on the baking sheets. Decorate each meringue with a candy eyeball. Dust with the matcha.
Transfer the meringues to the oven and bake 1 hour. Turn off the oven and let the meringues stand in the oven until dry, about 3 hours or overnight.