16tablespoons(2 sticks; 8 ounces) unsalted butter, one stick melted until browned
1cup+ 2 tablespoons dark brown sugar
2large eggs, at room temperature
In a medium sized bowl whisk together the flour, baking soda, and sea salt; set aside.
Place 8 tablespoons of butter in a small sauce pan over medium-high heat and cook for about 2 minutes – stirring almost constantly – until the butter has browned. Remove from heat and stir in remaining butter; whisk until completely smooth. Place the bowl in the refrigerator or freezer and bring the butter back to room temperature. *You’ll know the butter is at room temperature when you press a finger into the top and it makes a slight indentation.
Once the butter is at room temperature… Preheat oven to 375 degrees (F). Line 2 large baking sheets with parchment paper and set aside.
Add the sugars and the vanilla to the browned butter and whisk until light and fluffy; about 2 minutes (you may use a stand-mixer or handheld mixer to help if you have one).
Add the eggs and beat quickly – for only about 30 seconds – until they’re just combined. Let the mixture rest for 5 minutes, then beat the eggs for another 30 seconds.
Gently fold in the flour mixture with a wooden spoon, stirring only until the flour begins to disappear. Fold in m&m's.
Roll 3 tablespoon sized balls of dough between your palms to form a ball (they should be big; almost a 1/4 cup), then place on prepared sheet (make sure to leave enough room in between each cookie for inevitable spreading).
Continue this process until all the dough has been rolled. Place baking sheets in preheated oven and bake for 11-13 minutes, or until golden at the edges but still soft in the middle. Press additional m&m's on top of the cookies right after removing the pan from the oven, if desired.
Let cookies cool for 5 minutes on the sheet before transferring to a wire wrack to cool completely.