In a large skillet cook sausage over medium heat about 8 minutes or until brown, turning often. Drain on paper towels. Slice into bite-size pieces.
Grease a 2-quart oval or square baking dish; set aside. In a large bowl combine sausage, spinach, beans, onion, and evaporated milk, ¼ cup of the Romano or Parmesan cheese, the lemon peel, lemon juice, ground nutmeg, and pepper.
Spoon into prepared baking dish.
For topping, in a small bowl combine bread crumbs, remaining Romano or Parmesan cheese, garlic, and melted butter or margarine; sprinkle atop casserole.
Bake at 375°, about 35 minutes or until heated through.