Preheat the oven to 350 F. Line 2 baking sheets with parchment paper or silicone baking mats.
Microwave the butter in a large, microwave-safe bowl for about 40 seconds. Butter should mostly melted.
Whisk the butter until it is completely melted.
Add the sugars; mix until well-combined.
Stir in vanilla and egg until incorporated.
Add the flour, cocoa powder, baking soda, and salt. Please read the recipe note about properly measuring flour.
Mix dough until just combined. Dough should be soft and a little sticky but not overly sticky.
Stir in chocolate chips.
Scoop out 1.5 tablespoons of dough (medium cookie scoop).
Dip the top of the cookie dough into the sprinkles.
Gently press 2 candy eyes into the top of the dough.
Place dough 2 inches apart on baking sheet.
Bake for 7-10 minutes, or until cookies are set. They will be puffy and still look a little underbaked in the middle.3
Notes
Flour: Be sure to fluff and then scoop and sweep to measure the flour. Too much flour will result in a dry or crumbly cookie.
Cocoa powder: I use regular unsweetened cocoa powder, not Dutch-processed.
Candy eyes: I bought a package with small, medium, and large candy eyes. I used the smallest sized eyes for these cookies.
Sprinkles: Just dip the tops into the sprinkles but don't roll the entire cookie in sprinkles. Sprinkles on the bottom of the cookie can melt as the cookies bake.
Don't over-bake the cookies, or you won't end up with soft cookies. Since oven temps can vary, I suggest starting with the listed baking time and increasing the time as needed.