Potluck Chicken Tetrazzini

Name: Potluck Chicken Tetrazzini
Cuisine: European, American
Ingredients: 1 purchased roasted chicken (good dish for leftover chicken or boneless chicken breasts); 8 ounces dried spaghetti or linguine, broken in half (whole grain pasta for health conscience); 12 ounces fresh asparagus, trimmed and cut into 1-inch pieces; 8 ounces small whole fresh mushrooms; 3 medium red and/or yellow sweet peppers, seeded and cut into 1-inch pieces; 2 tablespoons butter (or olive oil); 1/4 cup all-purpose flour; 1/8 teaspoon black pepper; 1 14 ounce can chicken broth; 3/4 cup milk; 1/2 cup shredded Swiss cheese (2 oz.); 1 tablespoon finely shredded lemon peel; 2 slices sourdough bread, cut into cubes (about 1-1/2 cups) (optional); 1 tablespoon olive oil; 2 tablespoons snipped fresh parsley