01 - Preheat oven to 350°F. Grease a 24-cup mini muffin tin thoroughly.
02 - In a large bowl, cream together unsalted 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 all-purpose flour, baking soda, and salt until well blended.
05 - Gradually add the dry ingredients to the wet mixture, mixing on low speed until just combined. Avoid overmixing.
06 - Fold the semisweet chocolate chips into the dough using a spatula.
07 - Scoop approximately 1 tablespoon of dough into each mini muffin cup. Press the dough down slightly with your fingers to create a shallow well.
08 - Bake for 10 to 12 minutes, or until the edges are lightly golden.
09 - Remove the tin from the oven and immediately use the back of a spoon to gently press down the centers of the cookies to reinforce the cup shape.
10 - Allow the cookie cups to cool in the pan for 10 minutes before transferring them to a wire rack to cool completely.
11 - Beat the softened butter until smooth. Gradually add powdered sugar, alternating with milk, until the frosting is fluffy. Stir in the vanilla extract.
12 - Divide the frosting into three separate bowls. Keep one bowl white, and tint the remaining two with red and blue gel food coloring.
13 - Pipe or spoon the colored frosting into the cooled cookie cups. Finish by topping with red, white, and blue sprinkles.