01 -
Preheat oven to 350°F (177°C). Lightly grease three 12-cup mini muffin pans.
02 -
In a large bowl, combine cake mix, eggs, vegetable oil, and black food coloring if desired. Stir until uniform.
03 -
Using a 1/2 tablespoon (7 g) scoop, place dough into each mini muffin cup. Flatten dough gently with fingers to prevent doming. Bake 8-10 minutes until edges are set.
04 -
Immediately after removing from oven, press a 1 tablespoon (15 ml) measuring spoon into the center of each warm cookie to create an indentation. Cool completely in pans before removing.
05 -
Beat softened butter until creamy. Gradually add powdered sugar, vanilla, and salt, beating until smooth. Add milk one tablespoon at a time until filling achieves a pipeable consistency. Stir in green food coloring to desired shade.
06 -
Fill each cooled cookie cup with green buttercream, piping to mimic bubbling potion.
07 -
Sprinkle round green sprinkles atop buttercream. Add candy eyeballs and Halloween sprinkles as desired. Insert halved pretzel sticks into each cup to resemble stir sticks.
08 -
Serve immediately or store in an airtight container at room temperature for up to 3-4 days or refrigerated for up to one week.