Using a stand or a hand mixer, cream together the butter & sugars for 2-3 minutes.

If you're using a stand mixer and your hands are free, you can whisk together the dry ingredients (flour, baking soda, salt) in a separate mixing bowl and set aside.

Add the vanilla & egg to the creamed butter/sugar & mix briefly - just until the egg is blended in. Scrape the sides of the bowl to make sure everything is evenly mixed.

Gently add in the flour mixture and mix just until blended.

Fold in the chocolate chips.

Gently add in the M&Ms - they're prone to breaking if you mix them too hard, so just give them a little stir into the dough.

Transfer the cookie dough from the mixing bowl into another bowl, cover with plastic wrap, and set in the fridge to begin chilling.

Using a stand or a hand mixer, cream together the butter & sugars for 2-3 minutes.

If you're using a stand mixer and your hands are free, you can whisk together the dry ingredients (flour, cocoa, baking soda, salt) in a separate mixing bowl and set aside.

Add the vanilla & egg to the creamed butter/sugar & mix briefly - just until the egg is blended in. Scrape the sides of the bowl to make sure everything is evenly mixed.

Gently add in the flour mixture and mix just until blended.

Fold in the chocolate chips (semisweet & white).

Gently add the M&Ms - same drill as the chocolate chip cookie dough recipe!

Cover the cookie dough with plastic wrap, and set in the fridge to begin chilling.

Chill BOTH cookie doughs (covered with plastic wrap) for at least 1 hour. You can chill for longer, but make sure to put them in the fridge for at least an hour. Believe me, this makes a HUGE difference in flavor & texture!

Remove dough from fridge & preheat oven to 375.

Pinch together a bit from each dough, then roll together into a ball. If you want more chocolate chips & M&Ms poking out of the dough after baking, add a few more to each dough ball.

Keep going until you have a dozen on a cookie pan, and then add the pan to the oven and bake for 9 minutes.

Repeat for remaining dough!

(If I can get it just right, I can end up making 24 cookies out of this, but I often end up getting about 28 out of it. If you want an even 2 dozen, just add a little bit of extra dough to each dough ball to make them slightly bigger.)