This should be a soft white square bread, preferably without the crust. Or crust could be trimmed.
If you are located in the US, I like using Pepperidge Farms white breads. Just cut off the crusts.
I've only ever seen crustless white bread at a Walmart, in Texas.
My Publix bakery slices their Tuscan Boules on the "thin" rather than "regular" sandwich slice thickness, and it is a delicious bread with good body to hold up to your variety of mezze fillings.You will have to pare the crust yourself,but you'll end up with a good bread to enhance any of your fillings.
I see that you can buy tremezzini bread online from various sites including Amazon (natch!). Some are imported from Italy.
Importing "tramezzini" bread from Italy is a bridge to far, and a colossal waste of money. In Rome they use nothing more elaborate than a pullman loaf.
I'm a late convert to "texas toast" for this type of sandwich. It has a good structure which works well with pain perdu as well as grilled cheese.
You're right about that, pierino -- a waste of money. I overlooked jane bartell's request for AMERICAN bread that would be suitable. But what is Texas Toast exactly, other than a marketing scheme? I tried some once but found it to be "meh." What am I missing?
You are not missing anything. It took me awhile to accept it for what it is because my first encounters with Texas Toast involved some poorly conceived restaurant plates.
The Italian bread used for a tramezzino is pancarrè. If you are a halfway decent baker it's pretty easy to make yourself. There's a good recipe in "The Italian Baker" by Carol Field.
Having said all that, a tramezzino would not be the first snack I would go looking for if I flew back to Rome tomorrow. It's typically just white bread slathered with a lot of mayonnaise and maybe including some egg salad and/or other topping.