In bowl, combine crumbs, melted butter, parsley, 1 teaspoons salt and 1/2 teaspoons black pepper. In 4 quart pot over medium heat; cook pancetta 8 minutes. Transfer to small bowl; reserve fat.
Cook cauliflower in batches 10-12 minutes, adding up to 3 tablespoons butter if needed. Transfer to bowl. Deglaze pot with 2 tablespoons water; add to cauliflower. Wash pot.
In same pot over medium heat, melt 3 tablespoons butter. Cook flour 3 minutes. Whisk in wine and milk; cook 10 minutes. Stir in cheeses, 2 teaspoons salt, 1 teaspoons black pepper, cayenne, nutmeg and cream, then cooked pasta, pancetta and cauliflower. Top with bread crumbs., Bake 30 minutes, broil 4-5 minutes.