• BRING ½ cup of butter and ½ cup of cream cheese to cool room temperature. (See note #1.)
• PREHEAT the oven to 350°F (175°C) and line a baking sheet with parchment paper. (See note #2.)
• CREAM ½ cup of butter and ½ cup of cream cheese in a large mixing bowl with an electric hand mixer until smooth.
• ADD the cold egg into the wet ingredients and mix until incorporated.
• POUR in the dry cake mix and mix until it is combined. Use a spatula to scrape the sides of the bowl to make sure all the dry ingredients are combined into the cookie dough.
• STIR in 2 tablespoons of sprinkles.
• SCOOP the cookie dough balls with a large scoop (2 tablespoons size is ideal). Roll the dough ball in your hands to make it smooth. (See note #3.)
• SLIGHTLY FLATTEN the balls between the palms of your hands.
• PLACE the cookie dough balls about two inches apart on the lined baking sheet.
• BAKE in the oven for 11 to 13 minutes, or until the edges are done. The middles may not look completely done, but they will finish baking with the residual heat when they are out of the oven.
• REMOVE the cookie sheet from the oven and turn the oven off.
• SHAPE the cookies uniformly. Use a round cookie ring that is larger than the size of the cookie. (A cookie ring is essentially a round cookie cutter.)

  Position the cookie ring around the warm cookie, ensuring that the ring completely encircles the cookie. With the cookie inside the ring, start rotating the ring around the cookie. Continue rotating for about 10 seconds.

  As you rotate, you'll notice the sides of the cookie pulling in, and the cookie gradually becoming rounder and more uniform in shape. The warmth of the cookie will help it conform to the ring.

  By the end of the rotation, the cookie should have taken on a perfectly round shape. Repeat this technique with all the cookies. (See note #4.)
• PLACE the cookie sheet on a wire rack and cool for 5 minutes.
• TRANSFER the cookies from the cookie sheet to the cooling rack. Cool them completely.

Make the Frosting

• CUT ½ cup of cold butter (straight from the fridge) into pieces and add it to a large mixing bowl. Beat the butter with electric beaters until it starts to soften.
• COMBINE half of the powdered sugar with the butter. Beat until the powder sugar is crumbly and absorbed into the butter. Then add the rest of the sugar. Beat again until it is crumbly and there isn't any powdered sugar on the bottom of the bowl. It will look crumbly.
• ADD ¼ cup of cool, room temperature cream cheese and mix until combined.
• USE the frosting right away. Or refrigerate it until you're ready to frost the cookies. (See note #5 if you chill the frosting.)

Decorate the Cookies

• SPREAD about 1 tablespoon of frosting on each cooled cookie.
• SPRINKLE each cookie with Funfetti sprinkles.
• SERVE right away.