Peel the potatoes and cut into 1" chunks. Boil until tender and drain. Mash potatoes and add 6 TBS of the butter and then the milk. Stir and whip until potatoes are smooth.
Add mozzarella, romano cheese and salami. Stir to blend. Add salt and pepper to taste.
Use 1 TB of the remaining butter to grease the bottom and sides of a high-sided casserole dish. Coat the bottom and sides with breadcrumbs. Spoon potato mixture into the dish and dot the top with the butter.
Bake at 350° until the top is golden brown. Be careful -- this dish is VERY hot when it comes out of the oven!