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 light and fluffy.
03 - Beat in eggs one at a time, then add vanilla extract, mixing well.
04 - In a separate bowl, whisk together all-purpose flour, baking soda, and salt.
05 - Gradually add dry ingredients to the wet ingredients, mixing until just combined.
06 - Fold semisweet chocolate chips into the dough.
07 - Scoop about 1 tablespoon of dough into each muffin cup, pressing slightly to form a cup shape.
08 - Bake for 10-12 minutes until lightly golden.
09 - Remove from oven and immediately use the back of a spoon to gently press down the centers to form a deeper cup shape.
10 - Cool the cookie cups in the pan for 10 minutes, then transfer to a wire rack to cool completely.
11 - Beat unsalted butter until smooth. Gradually add powdered sugar, alternating with milk, until fluffy. Mix in vanilla extract.
12 - Divide frosting into three portions. Leave one plain, tint one with red food coloring, and one with blue.
13 - Pipe or spoon frosting into cooled cookie cups. Decorate with red, white, and blue sprinkles.