01 -
Preheat oven to 350°F. Lightly grease three 12-count mini muffin pans.
02 -
In a large bowl, combine cake mix, eggs, oil, and black food coloring if using; mix until smooth.
03 -
Scoop about 1/2 tablespoon of dough into each mini muffin cup; flatten with fingers. Bake 8-10 minutes until edges are set.
04 -
Remove from oven and immediately press an indentation in each warm cookie using the back of a 1 tablespoon measuring spoon. Cool completely.
05 -
Beat butter in a medium bowl until creamy. Gradually add powdered sugar, vanilla, and salt; beat until smooth. Add milk gradually until smooth and pipeable. Stir in green food coloring to desired shade.
06 -
Pipe green buttercream into cooled cookie cups to resemble bubbling potions. Decorate with green sprinkles, candy eyeballs, and Halloween sprinkles. Break pretzel sticks in half and insert as stir sticks.