Nothing incredibly original or stretching my skills here, but a good, quick snack nonetheless.
Luckily, I have a couple of good bagel stores in walking distance to get fresh bagels. (No pre-packaged, mini-bagels here!) And I can also get a fresh mozzarella, with or without salt. (We prefer without -- you can always add it if you need to.)
I didn't have any pizza sauce or leftover sauce from pasta, and I wasn't going to open a can of tomato sauce, figure out what spices I needed, for just two bagel halves. Next best thing, there was a bottle of BBQ sauce in the fridge from Dinosaur BBQ. A little on the spicy side, but that's a plus.
Cut open the bagel. Make a circular depression with your thumb going around the bagel. Put the bagel in the toaster oven and toast it for about half the time you normally would.
Spoon in BBQ sauce into the depression and spread it around. (Don't fill it like a trough.)
Cut up the mozzarella. Here's one time where the packaged stuff, particularly string cheese, might have been better. The fresh kind is a little watery, especially if you refrigerate it in water after you buy and use it the first time. I tried to dry the slice a little with paper towels. It worked a little.
Sprinkle some spices on top: garlic powder, onion powder, pepper, salt, whatever. Pop it back into the toaster oven and cook it some more. Watch that the cheese isn't burning ... or dripping all over the inside of the oven.