Preheat oven to 350° F. Line an 8 by 11-inch baking pan with parchment paper to overhang on opposite sides. Set aside.
Place graham crackers in the bowl of a food processor and grind into fine crumbs. Mix with melted butter and press into the bottom of the prepared pan.
Add chocolate, butterscotch, and white chocolate chips. Slowly pour the sweetened condensed milk over the chips. Follow this by the toasted nuts and coconut, and then the M&Ms. Use the bottom of a measuring cup or glass to press down somewhat firmly on the M&Ms to adhere them into the bars. Finish with flake salt.
Bake for 35-40 minutes or until set. Cool. Cut into small bars.
Notes
Bars will keep at room temperature in an airtight container for 3-4 days or in the refrigerator for up to one week.