Preheat the oven to 350°F. Line 2 large cookie sheets with a piece of parchment paper, and set them aside.

Use a whisk to mix the flour, cocoa powder, baking powder, and salt in a small or medium mixing bowl. Set the dry ingredients aside.

In a separate large mixing bowl, add light brown sugar, sugar, and butter. Cream the butter and sugars using an electric mixer at medium speed until the mixture is fluffy. Add the large egg and vanilla extract and continue mixing until smooth.

Pour in the dry ingredients and mix until everything is combined and the cookie dough is crumbly. Add the chocolate chips and M&Ms into the cookie dough and fold them in.

Use a 1-½ tablespoon cookie scoop to scoop the cookie dough and roll it into a ball in your hands. Repeat until all of the cookie dough has been used. Place the cookie dough balls on the parchment-lined cookie sheets about an inch and a half apart (I can fit 16 cookies onto one cookie sheet.)

Press a few more M&Ms on top of the cookies, then dip the tops of the dough balls in sprinkles, if desired.

Bake the cookies for 13-15 minutes or until they have puffed up on top and the outside looks crisp. Be careful not to overbake the cookies or they will be too tough.

As soon as the cookies come out of the oven, press 2-3 candy eyeballs on top of them. Be careful not to burn yourself on the hot cookies.

Let the cookies rest on the pan for 10 minutes, then transfer them to a cooking rack. Allow them to cool to room temperature before serving or storing them in an airtight container.