Rosemary Roasted Fall Veggies Gruyere and Sage Béchamel Lasagna

Name: Rosemary-Roasted Fall Veggies, Gruyere and Sage Béchamel Lasagna
Ingredients: 10 ounces lasagna noodles; 1 tablespoon olive oil, divided; 1 1/2 pounds mushrooms, quartered; 2 1/2 pounds sweet potatoes, peeled and cubed; 8 10 rosemary sprigs, leaves chopped; 1 1/2 teaspoons salt, divided; 2/3 cup flour; 6 cups milk; 3 cups chopped onions, divided; 1/4 cup chopped fresh sage; 6 garlic cloves, minced, divided; 1 bay leaf; 10 ounces frozen spinach, chopped; 4 ounces gruyere cheese, grated; 3 ounces parmesan cheese, grated