Arrange bottom half of the hamburger / slider buns in the prepared baking dish. Spread the mayonnaise over them.
Spoon the marinara sauce over them, dividing it equally. Sprinkle most of the chopped scallions over it.
Now, place one slice of the swiss cheese, then 2 oz ham slice (equally divide the 8 oz among the 4 hamburger or 8 slider buns) and one slice of cheddar cheese.
Top with the top of the bun.
Warm the butter and add the chopped garlic to it. Brush the top of the buns with this garlic butter.
Cover the baking dish, loosely, with foil and bake for 15 mins or so, till the cheese is all melted.
Remove from oven and top with rest of the scallions. Serve as it is or with some more marinara sauce for dipping.