Preheat oven to 400˚F. Lightly grease a small shallow baking dish 7-8 inches in diameter.
If you have large bread crumbs stored, you’re in business! But if you don’t, they are easy to make. Take a slice of sturdy bread, and grate it, or chop it, or whiz it in a blender, to produce rough craggy bread crumbs. Mince the garlic.
Heat a bit of oil or butter (or both) in a small skillet. Add the garlic and cook, stirring, until it is very fragrant but NOT brown. Add the bread crumbs and toss gently until the bread crumbs are coated. Set these aside while you grate or finely chop the cheese. (I like gruyere or aged Gouda best but Parmesan or Romano work very well also.)
Core the tomatoes and slice them about ¼ inch thick. Arrange half the tomato slices on the bottom of the dish, overlapping them only slightly. Use the ugliest pieces on the bottom, where they won’t be seen. Season with salt and pepper, add half the garlicky bread crumbs, then half cheese. Repeat: you’ll end up with two layers of tomatoes, each layer topped with bread crumbs and cheese.
Bake in a hot oven just until the crumbs are browned, the cheese is melted, and you can’t stand the good smell any more and have to attack it - that'll be about 15 minutes.
May be doubled, in which case use a larger pan. If you want more servings, use a larger dish, because you still need to make each layer 1 tomato slice thick, and keep it to at most three layers (2 is better). You want the tomatoes to heat through, but you do not want to burn the cheese and crumbs on top!