Preheat the oven to 350F. Line 2 large baking trays with silpat liners or parchment paper. Scoop the cookie dough into 1.5-tablespoon sized balls and arrange them on the prepared baking trays.
Bake the cookies until they are golden along the outside, about 12 to 15 minutes, rotating the trays once halfway through.
Let the cookies cool on the trays for 10 minutes and then use a thin metal spatula to transfer the cookies to a wire rack to finish cooling.
Finish cooking the remaining cookie dough the same way.
Mix together the vanilla frosting and red gel food coloring in a large bowl. Add more red coloring to achieve your desired color.
Cut each cookie in half. Spread each half with frosting.
For half of the cookies, arrange 6 mini marshmallows along the curved side, and place 1 mini marshmallow on the straight side. Top with the other frosted cookie halves.
Place 2 slivered almonds in the teeth for each set of dentures to create fangs. (It helps to dip 1 side of each slivered almond in frosting first to help it stick.)
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Notes
To make larger “dentures” simply make larger cookies. Note that you may need to adjust the cook time, and you will need more mini marshmallows.