Preheat your oven to 350°F (175°C).
Cream together the unsalted butter and granulated sugar until light and fluffy, about 2-3 minutes.
Beat in the egg and vanilla extract until well combined.
In a separate bowl, whisk together the all-purpose flour, baking soda, baking powder, and salt.
Gradually add the dry ingredients to the wet mixture, mixing until just combined.
Gently fold in the funfetti sprinkles until evenly distributed.
Portion out the dough into the muffin tin, filling each cup about halfway. Bake for 10-12 minutes until edges are lightly golden.
Allow the cookie cups to cool in the pan for 5 minutes before transferring to a wire rack to cool completely.
In a mixing bowl, beat together the powdered sugar, vanilla extract, and heavy whipping cream until smooth and creamy.
Once cooled, frost each cookie cup generously with the vanilla frosting and top with extra funfetti sprinkles.