Xmas M&M cookies

Using a hand mixer or stand mixer fitted with the paddle attachment, beat butter and sugars for 1-2 minutes. Add egg and vanilla, beating until combined, and scraping the sides and bottom of the bowl as necessary.. In a separate bowl whisk flour, cocoa powder, baking soda, and salt. Add dry ingredients to butter mixture and beat until just combined. Use a rubber spatula to stir in chocolate chips and ½ cup M&M's. At this point, I like to let the dough rest at cool room temp for 30 minutes before baking (this helps with the texture of the cookies). If your kitchen is warm you can place the dough in the refrigerator for 30 minutes. Preheat oven to 350°F. Line 2 baking sheets with parchment paper (don't skip this step, it helps keep the cookies from spreading). Scoop the dough into 2-tablespoon portions and form into mounds that are higher rather than wider. Place the dough mounds a few inches apart on parchment lined baking sheets. Lightly press the remaining ¼ cup M&M's onto the tops of the dough (this makes for a prettier cookie). Bake for 9-11* minutes, until the edges are beginning to set, but the rest of the cookie is still slightly underdone. Note: They should be so soft that you should not be able to pick them up off the baking sheet. They will set as the cool. Place the baking sheets on wire rack to cool completely. See note about shaping the cookies while they are still warm.