Preheat oven to 350°F. Line cookie sheets with parchment paper or silicone baking mats.

In a medium bowl, whisk together cocoa powder, baking soda, salt, and flour. Set aside.

In the bowl of an electric mixer fitted with the paddle attachment, cream butter and both sugars. Mix in egg and vanilla until smooth. Add dry ingredients and mix until combined. Mix in chocolate chips, peanuts (if using), and candy corn.

Scoop 2 tablespoon-sized balls of dough onto the cookie sheets, 3 inches apart. Ensure candy corn is fully enclosed within the dough.

Bake for 9 to 12 minutes until the edges are golden. Cool on cookie sheets at least 5 minutes before transferring to a wire rack.

Store cookies in an airtight container for up to 3 days or freeze for up to one month.