Prepare oven and dry ingredients: Preheat oven to 350°F and line a baking sheet with parchment paper. In a medium bowl, whisk together the flour, cocoa powder, baking soda, and salt. Set aside.
Mix wet ingredients: In a large mixing bowl, beat the softened butter, cream cheese, and sugar until smooth and creamy. Add the egg and vanilla extract, mixing until fully combined.
Combine and form dough: Gradually add the dry ingredients to the wet mixture and stir just until a soft dough forms.
Add Oreos and chocolate chips: Fold in the crushed Oreo cookies and chocolate chips (if using), stirring until evenly distributed.
Scoop, bake, and cool: Scoop dough onto the prepared baking sheet, spacing cookies 2 inches apart. Bake for 10–12 minutes, until edges are set and centers are soft. Let cool on the pan for 2–3 minutes, then transfer to a wire rack.