• In a stand mixer or with a hand mixer, cream butter, cream cheese, and sugar for 1-2 minutes on medium speed, until lightened and creamy.
• Add the egg and vanilla extract. Mix for another minute, until it's blended. Scrape the bottom of the bowl to be sure everything's well mixed.
• Add flour, baking powder, baking soda, and salt. Mix on low speed until dough is almost combined. Scrape the bottom of the bowl again to check for unmixed bits of butter or flour, then mix again briefly so the dough just comes together.
• If your dough is too soft to hand, refrigerate it for 20 minutes. Otherwise, start scooping.
• Place sprinkles in a bowl. Use a #40/ 1.5 tablespoon cookie scoop, or two spoons, to portion the cookie dough. Roll the dough briefly in your hands to make a rough ball. Then dip the top ½-2/3 of the ball in the sprinkles, coating it thickly.
• Place cookie dough, sprinkle-side up, on a parchment- or Silpat-lined cookie sheet about 2 inches apart. Use the bottom of a glass to flatten the cookies to ¼-1/2 inch thickness.
• Bake cookies for about 9-10 minutes at 375F. Cookies will be pale but will have begun to brown on bottom.
• Cool for 4-5 minutes on the baking sheet, then remove the cookies to a cooling rack. Once completely cooled, store in an airtight container.
• Store in an airtight container at room temperature for up to 3 days.

Make-Ahead

• Scoop the dough and roll in sprinkles as above. Place balls of dough on a plate or baking sheet lined with plastic wrap or waxed paper, then flatten each with a glass. Freeze.
• Once the cookies are completely frozen, remove them from the plate and store in a labeled freezer bag.
• To bake frozen dough: remove cookies from the freezer once your oven has preheated; no need to thaw. Place frozen dough on the prepared baking sheet and bake for about 11-12 minutes.