In a large mixing bowl, whisk together flour, baking soda, baking powder, and salt. This ensures that the dry ingredients are evenly combined and ready for the next steps.
In another large mixing bowl, mix together butter and granulated sugar. Beat until light and fluffy, about two minutes. This aerates the mixture, creating a light texture for your cookie cups.
Add in the egg and vanilla extract, mixing well until fully incorporated. This will add moisture and flavor to your cookies.
Now, add the dry ingredients all at once to the wet mixture. Mix for just five seconds to combine. Be careful not to overmix; you want to keep the dough tender.
Fold in the funfetti, mixing the dough until all the flour is incorporated. Avoid overmixing to keep the cookies soft.
Chill the dough in the fridge for at least two hours, preferably overnight. This step is crucial as it helps the flavors meld and the cookies maintain their shape while baking.
Preheat your oven to 375 degrees Fahrenheit. This ensures that your cookie cups bake evenly.
Spray a mini muffin pan with baking spray. This will help prevent sticking and ensure easy removal of the cookie cups.
Scoop the cookie dough using a small cookie scoop directly into the cups of your muffin pan. Fill them about ¾ full to allow for rising.
Bake the cookies for eight to ten minutes, keeping an eye on them. For me, nine minutes was the magic number. You want them lightly golden around the edges.
Cool the cookies for five minutes on the sheet. Then, transfer them onto a wire rack to cool completely. This helps them firm up and makes them easier to frost.
In a large mixing bowl, beat the butter with an electric mixer until creamy for the frosting. This step ensures a smooth texture before adding the sugar.
Add the powdered sugar gradually, sifting through a sieve right over the bowl, one cup at a time, mixing well after each addition.
Mix in the remaining vanilla and heavy whipping cream, beating for two minutes until the frosting is fluffy and easy to pipe.
Place the frosting into a piping bag and decorate your cooled cookie cups. Get creative and have fun with it!