GEeeeZa!
I can recommend the following. It might not be the most healthy choice, unless you burn some calories... But it's freaking awesome.
First off, you'll need some Ciabatta bread.
Alright, cut that shit in half, horizontally. So that you can make two sandwiches, you know.
Butter your sandwiches, then put some garlic powder on them, as well as some oregano.
Don't use too little butter, or I will come and haunt you when I die from crying over it.
OK, now grab some of this! MOZZARELLA!
Slice it up to pieces of above size and put them on your sandwich. Don't over-crowd the poor little bread.
If you get leftovers from the cheese, eat it or something. Perhaps make more sandwiches to others. Usually, you won't get much leftovers, though.
One of those small cheeses is usually just enough to make a couple of sandwiches.
OK, done with the worst part, I guess.
NEXT, take some friggin' tiny TOMATOES :O
Slice those red bastards up!!! And put them on top of the mozzarella. The cheese is gonna melt, so put them closer to the middle.
They'll drift out in the oven, some might even fall off.
OK, last ingredient. Put just a little liquid butter on top of the tomatoes. Trust me, this makes it so much better.
Last thing you do before the oven, just spray on some water onto the sandwich, it will help it to last longer in the oven somehow.
If you don't have a spray bottle with water in your kitchen, just sprinkle some on and rub the underside of the bread with water.
Last step. OVEN!!! The gates of Hell!
OK, the oven should be pre-heated to about 400 degrees Fahrenheit (or 200 degrees Celsius). Keep them in there for something between 8-12 minutes. It always depends.
They should be brown around the edges of the bread. Good and crusty, you know.
Put these puppies into the middle of the oven on a rack guard. Put something under it, because these things drip and tomatoes can fall off.
Whatever you do, don't use the microwave or some crazy stunt like that, it'll ruin everything.
Have fun! These are some tasty mozzarella & tomato hot sandwiches. Also, don't be afraid if there's some smoke.