I've made these a number of times and everyone always loves them. They are wonderful to make for a meal where there is no gravy or sauce to put over regular mashed potatoes and baked or fried potatoes just aren't quite right with the meal. Just make sure to get the least greasy hard salami you possibly can. You only need 1/8 pound, so get the best quality you can get. You don't want greasy pockets in the finished potatoes.
Peel the potatoes and cut into chunks. Boil until tender and drain. Mash potatoes and add 5 Tbs of the butter and then the milk. Stir and mash until the potatoes are smooth.
Add the mozzarella cubes, romano cheese, and salami. Stir to blend. Add salt and pepper to taste.
Use 1 TBS of the remaining butter to grease the bottom and sides of a high sided casserole dish. Coat the bottom and sides with breadcrumbs allowing the extra breadctumbs to lay in the bottom of the dish.
Spoon the potato mixture into the dish and dot the top with the remaining butter.
Bake at 350 degrees until the top is golden brown. Be careful -- this is VERY hot when it comes out of the oven.