When I was a kid my Mom would make open faced sandwiches. She took slices of bread and topped them with cheese then a slice of tomato. She would bake or broil them, not sure which. I had one of my cravings and tried my variation.
Took two slices of Corn Harvest GF bread and topped them with rice milk mozarella cheese (it isn't casein free unfortunately) and then a slice of tomato topped with pepper and basil. I baked them at 400 degrees for 10 minutes. My craving was satisfied.