1 cup unsalted butter, softened to room temperature
1 1/2 cups granulated sugar
1 large egg
1 1/2 teaspoons vanilla extract
1/2 teaspoon almond extract (optional)
2 1/2 cups all-purpose flour
1 teaspoon baking powder
1/2 teaspoon salt
1 can (16 oz) vanilla frosting or homemade buttercream
Neon green, purple, or orange food coloring
1/2 cup assorted candy eyeballs (various sizes)
Instructions
Preheat your oven to 350°F (175°C). Line a 9×13 inch baking pan with parchment paper, leaving a little overhang on the sides for easy removal, or grease the pan thoroughly with non-stick cooking spray.
In a large mixing bowl or using a stand mixer, cream together the softened butter and granulated sugar until the mixture is light and fluffy. This usually takes about 2 to 3 minutes of mixing on medium speed.
Beat in the egg, vanilla extract, and almond extract. Continue mixing until the ingredients are fully combined and the batter looks smooth.
In a separate small bowl, whisk together the flour, baking powder, and salt. Gradually add the dry ingredients to the wet mixture, mixing on low speed just until a soft dough forms. Be careful not to overmix at this stage.
Press the cookie dough evenly into the prepared 9×13 pan. Bake for 20 to 25 minutes, or until the edges are very lightly golden brown. The center should look set but still soft. Remove from the oven and let the bars cool completely in the pan.
Divide your frosting into different bowls if you want multiple colors, or keep it in one bowl for a single-colored monster look. Add a few drops of food coloring and stir until you reach your desired vibrant shade.
Once the cookie base is totally cool, spread the frosting evenly over the top. Immediately press the candy eyeballs into the frosting in random patterns—some close together, some far apart—to give your monsters character. Lift the bars out of the pan using the parchment paper and cut into 24 squares.