Step 1

In a large mixing bowl, whisk together the flour, baking soda, and salt. Set aside.

Step 2

In the bowl of a stand mixer fitted with the paddle attachment, or in a large mixing bowl using an electric mixer, cream together the butter, brown sugar, and granulated sugar for 1 to 2 minutes or until well combined. Add the eggs and vanilla extract one at a time and mix until fully combined.

Step 3

Slowly mix in the dry ingredients and continue mixing until just combined, making sure to stop and scrape down the sides of the bowl as needed. Mix in the chocolate chips on low speed, then add the M&Ms and gently fold them into the cookie dough.

Step 4

Cover the cookie dough tightly and transfer to the refrigerator to chill for at least 2 hours.

Step 5

Once the dough is almost chilled, preheat the oven to 350°F (177°C). Line large baking sheets with parchment paper or silicone baking mats and set aside.

Step 6

Remove the cookie dough from the refrigerator, using a 1.5 tablespoon cookie scoop, scoop the cookie dough and drop onto the prepared baking sheets. Make sure to leave a little room between each ball of cookie dough as they will spread a little while they bake.

Step 7

Bake in separate batches at 350°F for 10 to 12 minutes or until the edges of the cookies are lightly golden brown and the tops are set.

Step 8

Remove from the oven and cool on the baking sheet for 5 minutes, then transfer the cookies to a wire rack to cool completely.