Preheat oven to 350°F (175°C). Line a baking sheet with parchment paper and set aside.
In a large bowl, combine the white cake mix, softened butter, egg, peppermint extract, vanilla extract, and softened cream cheese. Use a hand mixer on medium speed until a soft dough forms and ingredients are fully incorporated, scraping the bowl as needed.
Gently fold in the chopped Oreo cookie pieces, Peppermint Crunch pieces, and dark chocolate chips until evenly distributed throughout the dough.
Cover the bowl and chill the dough in the refrigerator for 30 to 60 minutes.
Using a cookie scoop (about 1.5 tablespoons), form roughly 24 cookie balls. Roll them gently between your palms to shape and place them about 2 inches apart on the prepared baking sheet.
Bake for 10 minutes. The cookies will look slightly underdone in the center — this is perfect. They will set as they cool.
Remove from the oven and let cookies sit on the baking sheet for 2–3 minutes to finish baking and set. Then transfer them to a parchment-lined cooling rack or surface.
Gently press each cookie down with a spatula to flatten slightly for a classic cookie shape. Let cool completely before serving.
Store cooled cookies in an airtight container at room temperature for up to 5 days, or freeze for up to 2 months.
Notes
Use room-temperature butter and cream cheese for easy mixing. Don’t skip chilling the dough to prevent over-spreading.