Preheat your oven to 350 degrees. Cut butter into large pieces and place in the bowl of your electric mixer. Use the paddle attachment and cream the butter on medium for 3-4 minutes until it’s light and fluffy.
Add both sugars and the vanilla extract. Mix on medium speed until combined. Then beat on medium high for 3-4 minutes. While the butter and sugars are mixing, measure the flour, baking soda, and salt into a medium mixing bowl. Gently whisk dry ingredients to combine and set aside.
Turn your mixer off and using a rubber spatula scrape down the sides and bottom of the bowl. Add both eggs and mix on medium until combined. Turn off the mixer again and scrape down the sides and bottom of the bowl once more.
Add the dry ingredients and turn the mixer back on to medium low and mix until just combined. Turn of your mixer and remove the bowl from the stand. Now add your m and m’s and mix by hand with a rubber spatula.
Line your baking sheets with parchment paper. I like to use a medium ice cream/cookie dough scoop. Place the the cookie dough a few inches apart and gently, slightly press each ball down with the palm of your hand.
Bake cookies for about 10 minutes or until they are beginning to brown a little. Remove from oven and allow them to cool a couple of minutes before transferring them to a wire cooling rack.