Preheat your oven to 350°F (175°C) and grease three mini muffin pans with baking spray or butter.

In a large mixing bowl, combine the Devil’s Food Cake mix, eggs, canola or vegetable oil, and optional black food coloring. Mix until smooth.

Measure about 1/2 tablespoon of cookie dough into each muffin cup and flatten gently.

Bake for 8 to 10 minutes, then lightly press the back of a measuring spoon into each warm cookie to create indentations.

Allow cookies to cool in the pans for about 5 minutes, then transfer to a wire rack to cool completely.

Beat the unsalted butter until creamy in a mixing bowl. Gradually add powdered sugar, vanilla extract, and salt until combined and fluffy.

Slowly add milk to achieve a smooth buttercream consistency, then mix in green food coloring until desired color is reached.

Pipe the green buttercream into each cooled cookie cup, decorating to your liking.

Sprinkle with green or Halloween sprinkles and add candy eyeballs and pretzel sticks for decoration.