Servings: 12 servings.
1/3 cup butter, cubed 1 medium onion, chopped 1 garlic clove, minced 1/2 cup all-purpose flour 1 teaspoon salt 3-1/2 cups 2% milk 4 cups shredded part-skim mozzarella cheese, divided 1 cup grated Parmesan cheese, divided 1 teaspoon dried basil 1 teaspoon dried oregano 1/2 teaspoon white pepper 1 carton (15 ounces) whole-milk ricotta cheese 1 tablespoon minced fresh parsley 9 lasagna noodles, cooked and drained 2 packages (10 ounces each) frozen chopped spinach, thawed and squeezed dry 1 jar (8.1 ounces) prepared pesto
