Melt butter in a medium saucepan over low heat. Increase heat to medium and cook, stirring constantly, 7 to 10 minutes or until butter turns a deep golden brown along the bottom of the saucepan and smells nutty.
Immediately transfer butter to a clean bowl; cool completely.
Preheat oven to 350°F. Add butter, granulated sugar, and brown sugar to the bowl of a stand mixer fitted with the paddle attachment. Beat 2 minutes.
Add eggs, one at a time, beating well after each addition. Add vanilla, beating to combine.
In a separate bowl whisk flour, salt, and baking soda. Slowly add flour mixture to butter mixture, and pulse until only a few streaks of flour remain (do not overmix).
Add m&ms, pretzels, pecans, marshmallows, and chocolate chips, and pulse until just combined.
Scoop cookies into uniform sizes, and place on prepared pans. Bake 10 to 12 minutes or until golden brown on the edges.
Remove from oven; sprinkle with sea salt, and let cool on pan before transferring to a cooling rack.