In a large bowl, cream together the butter, cream cheese, sugar, eggs, and extracts with a hand mixer or stand mixer. Mix until combined and creamy for 4-5 minutes.
With a spatula, scrape down the sides of the bowl and then add the flour, cocoa, corn starch, baking soda, and salt. Mix together on low/medium speed for one minute, until combined.
Refrigerate dough for two hours before baking. [YOU CANNOT SKIP THIS STEP.]
Preheat the oven to 350 degrees and line two baking sheets with parchment paper, or spray with non-stick cooking spray. You will need to bake the cookies in batches.
Pour the sprinkles into a medium bowl. Start rolling the chilled cookie dough with the palm of your hands into “tablespoon” size balls. Next, roll the balls into the bowl of sprinkles until coated on all sides.
Place the cookies onto the prepared baking sheet, spacing 2-inches apart.
Bake for 9-12 minutes. The cookies will look a little “wet" when they come out of the oven, but that is okay. Do not over bake them!
Allow cookies to cool on a baking sheet for 3-5 minutes before moving to a wire rack to cool completely.