Get started. Preheat the oven to 350 degrees F. Line a baking sheet with parchment paper or butter/spray.
Cream butter and wet ingredients. In a standing mixer or large bowl with electric beaters, cream the butter and two sugars until fluffy, about 2 minutes. Add one egg and beat again for 1 minute. Pour in the vanilla and beat one more time. Use a spatula to scrape the sides of the bowl.
Add dry ingredients. Stop the mixer and add cocoa powder, flour, baking soda and salt. Start mixing again until the ingredients are JUST together.
Finish with chocolate. Pour in the chocolate chips and beat for 20 seconds until you’ve got chocolate throughout the batter.
Bake. Use a cookie scoop or a rounded teaspoon to set 12 cookies on a baking sheet. While the cookies are baking, organize your reindeer decorations (pretzels, candy eyes and red M&Ms). Bake for 12 MINUTES ONLY.
Add reindeer. Carefully remove pan from oven. Add two pretzels, two eyes and one M&M to each cookie. Place back in oven and bake for 3 additional minutes.
Cool. Remove from the oven and allow to cool on a wire rack for about 5 minutes.