In a mixer, blend your softened butter and brown sugar
Whip that until it's fluffy
To this mixture, add in your vanilla, until combined
Next, add in the baked flour and sweetened condensed milk, alternating the two
Mix in the chocolate chips and m&m's
Line an 8x8 baking dish with parchment paper
Cover your bars with foil and freeze for a couple hours
Using the peanut butter and 1/2 cup chocolate chips, make the frosting
Remove the bars from the freezer and spread the topping over the cookie dough
Put the foil back on the bars and freeze, allowing the topping to harden for about an hour
Cut into pieces and enjoy!