Preheat oven to 350˚F. Line 9x13 pan with foil and spray with baking spray.
Line bottom of pan with graham crackers. You may have to break them in order to fit.
Melt butter and brown sugar together. Bring to boil, and cook for 2-3 minutes. (It's helpful to use a thermometer - the mixture should get to a temp between 270˚F -290˚F)
Pour over graham crumbs. Bake 7 min.
Remove from oven, sprinkle chocolate chips - bake 1 minute to melt.
Remove from oven, smooth out chocolate and sprinkle with desired toppings.
Cool at room temperature, then transfer to refrigerator to harden (about 30 minutes)
Remove from pan and peel away foil (or parchment). Place on cutting board and slice.