From Kim Pierce
Preheat the oven broiler. Microwave the butter on High (100 percent power) just long enough to soften, but not melt; a stick takes 15 to 20 seconds. Smear the butter on one side of each piece of bread; you need only a thin coating, or alternating thin-thick dabs.
Dust with cinnamon, preferably in a mottled pattern, rather than evenly. Finish by layering the sugar on top, about ½ to 1 tablespoon, depending on the size of the bread slice. Place under the hot broiler. Remove when the tops are sizzling and the edges of the crust are one step away from burning. Serve with Mexican hot chocolate.
Note: If you're a toast purist, toast the bottom sides before buttering and seasoning the tops.