Preheat oven to 350Line an 8-by-8-inch baking pan with aluminum foil and spray with cooking spray; set aside.
Melt the butter in a medium bowl. Add the graham crackers and mix with the butter.
Pour the mixture into the pan, pressing the graham crackers down so the crumbs are packed down.
Evenly sprinkle with most of the chocolate chips, peanut butter chips, coconut, and peanut butter cups. I set aside some of these toppings for the end, as well. Drizzle the sweetened condensed milk over the top.
Sprinkle the remaining chocolate chips, peanut butter chips, and peanut butter cups on top.
Bake for about 25 to 30 minutes, or until lightly golden brown around edges and the center is mostly set.
Drizzle the melted peanut butter evenly over the top of the bars.
Place pan on a wire rack and allow bars to cool in pan for at least 2 hours, or overnight, before slicing and serving. The bars firm up as they cool.