01 - Preheat oven to 350°F. Grease a 24-cup mini muffin tin thoroughly.
02 - In a large bowl, cream together the softened butter, brown sugar, and granulated sugar until the mixture is light and fluffy.
03 - Beat in the eggs one at a time, ensuring each is fully incorporated before adding the next. Stir in the vanilla extract.
04 - In a separate bowl, whisk together the flour, baking soda, and salt.
05 - Gradually add the dry ingredients to the wet mixture, mixing until just combined. Fold in the chocolate chips.
06 - Scoop about 1 tablespoon of dough into each muffin cup. Press the dough down slightly with your fingers to create a shallow well.
07 - Bake for 10 to 12 minutes, or until the edges are lightly golden.
08 - Remove from the oven and immediately use the back of a teaspoon to gently press down the center of each cookie to reinforce the cup shape.
09 - Allow the cookie cups to cool in the pan for 10 minutes before transferring them to a wire rack to cool completely.
10 - Beat the softened butter until smooth. Gradually add powdered sugar, alternating with milk, until the frosting is fluffy. Mix in the vanilla extract.
11 - Divide the frosting into three separate bowls. Tint one portion with red food coloring, one with blue, and leave one portion plain.
12 - Pipe or spoon the colored frosting into the cooled cookie cups. Top immediately with red, white, and blue sprinkles.