Preheat oven to 350 degrees. Prepare 13x9 baking dish with non stick spray or line the bottom with foil and spray the foil for easy release.
In a medium sized bowl, add the melted peanut butter and sweetened condensed milk; mix until combined. Set aside.
Using a food processor, or a plastic bag and rolling pin, crush the graham crackers into about 1 1/2 cups of crumbs. Mix the crumbs together with the melted butter and then press the mixture into the bottom of the prepared pan.
Spread the chocolate chips/chunks, toffee and coconut onto the crust and then pour the peanut butter/milk mixture all over the top. Top with the M&MS.
Bake for 25-30 minutes, until the top is golden brown. Cool completely before cutting.
For presentation, you can melt 1/2 cup of chocolate chips with 1/2 tbsp of vegetable oil in the microwave. Cook for 15 seconds at a time, stirring between each time; until completely melted. Using a fork, drizzle the chocolate all over the top of the bars and chill them for 15 minutes to set the chocolate.