When I was a kid, we weren't allowed to use the stove or oven, but the microwave was free game. My brother and I often made English muffin pizzas by spreading Ragu sauce on an English muffin, sprinkling on some shredded mozzarella cheese and, in my case anyway, some canned mushrooms, then nuking them for about 30 seconds each.
Later, I modified this recipe by using tortillas rather than English muffins. I would spread the sauce on the tortilla, sprinkle on cheese, make a line of mushrooms down the center, microwave for 30 to 60 seconds, then roll up the tortilla into a tube for easier consumption.
Right at the moment, I lack both English muffins and tortillas, so instead, I think I will have to make pizza toast! I'm pretty sure this is the reason I have a toaster oven. Spread some leftover spaghetti sauce that's been sitting in my fridge for far too long, yet remains mysteriously un-moldy, on a piece of regular old sliced bread, then sprinkle on some shredded Mexican blend cheese because it's the cheapest I could find at the store, followed by some fresh mushrooms that I bought for lunch-salads this next week (I really like mushrooms), then put the creation in the toaster oven until the cheese is melted. Et voila! Pizza toast.
It's cheap! It's easy! It doesn't involve many ingredients! I've often been forced to leave off the mushrooms due to a lack of mushrooms in my cupboard. (Sigh.) I think my brother used to use sausage, too, and I know my friends have used pepperoni. When I made pizza tortillas, I would sometimes put vegetables on, too, in order to make them slightly more nutritious, or at least to add vegetables to my slim and limited diet.
I think I've made a few too many burritos and quesadillas lately, so pizza toast may be my new go-to quick and dirty meal item. Time will tell.