A cookie bar for anyone

Cookie bars, are, in my opinion, the perfect holiday-family-buffet-style-dinner-with-distant-relatives recipe. They are so very American, very easy, guilt-inducing. Most are simple to bake and their undecorated, gooey appearance reassures the casual snacker that these are not fancy treats. No need for a plate or a fork, just grab a few on a napkin and enjoy.
The kind I make vary depending on the snackers and I'm not sure where I first read this recipe, because I now just make it from memory. Hub likes peanut butter, so his have lots of PB chips. I like toffee in mine. When I make them for the holidays, I usually use butterscotch chips, pecans and shredded coconut (or whatever I have on hand that melts into gooey sweetness)
Ingredients:
Casserole dish, any size
Graham Cracker crumbs (enough to cover the casserole dish you're using)
1 Can Sweetened Condensed Milk
Bag of various chips (chocolate, PB, butterscoth, etc)
More toppings (nuts, shredded coconut, etc)
Directions:
Preheat oven to 350ish. Thoroughly butter casserole dish, bottom and sides. Cover bottom with crumbs. Pour on condensed milk. Cover with various chips and toppings, making sure to cover every little spot of milk (otherwise it bubles to the surface and covers up your pretty toppings. Bake, until the chips look soft around the edges or your coconut is nice and toasted.
Let cool, if you can stand it. Cut into huge hunks for yourself, small bites for others.