Line cookie sheets with silicone or a piece of parchment paper. Preheat your oven to 350 degrees.

Combine butter and sugar in a large bowl. Beat with an electric hand mixer at medium speed for 2-3 minutes. Beat in the eggs and vanilla.

Whisk together flour, cocoa, baking powder, baking soda, and salt in a medium bowl; stir them into the creamed mixture.

Roll the dough into 1 1/2" balls. Place them 3" apart on a prepared baking sheet. Flatten with a glass dipped in sugar to about 1/4 inch thick.

Pinch the top of the cookies to form kitty cat ears. Press fork into the sides of the cookie to make whiskers.

Bake cookies at 350° for 8-10 minutes. Immediately press on candy corn eyes and M&M noses.

Let cool on the pan for 3-5 minutes, then transfer to a wire rack to cool completely.