Preheat the oven to 225 degrees F.
In a stand mixer with the whisk attachment or in a large bowl with an electric mixer, whip the egg whites on high speed until they become frothy, about a minute or so.
With the mixer on medium-high, gradually add in the sugar, then add in the cream of tartar.
Increase the mixer to high and whip until stiff peaks form, about 3-4 minutes more.
Line a baking sheet with parchment paper. Carefully add the meringue to a prepared piping bag.
Continually press the meringue mixture directly down onto the lined baking sheet.
Press down and lift up to create layered stacks for each ghost (release the pressure just a tiny bit, pulling up on your frosting bag at the same time in between each layer).
Bake them for about 45 minutes or until the tops become a little brown.
Allow meringues to cool completely before decorating. With a toothpick, dip one end into the black gel food coloring and creating eyes and a mouth with long, flat-side of the pick.