Asparagus pesto lasagna

1/3 cup all-purpose flour
3 1/2 cups low-fat milk, divided
6 Tbs. pesto*, or more to taste
2 Tbs. grated Parmesan cheese, plus additional for garnish, optional
1 tsp. salt
1/4 tsp. ground black pepper
2 tsp. olive oil
1 1/4 lb. asparagus spears, tips cut off and reserved, spears trimmed and chopped into 1/4-inch pieces
1 clove garlic, minced (about 1 tsp.)
16 no-cook lasagna noodles (9 oz.)
2 cups shredded Fontina or part-skim mozzarella cheese (8 oz.), divided

1. Preheat oven to 350F. Whisk flour and 1/2 cup milk in saucepan until smooth. Gradually whisk in remaining milk. Bring to a boil over medium heat, whisking constantly, and boil 1 minute, or until thickened. Remove from heat; stir in pesto, Parmesan, salt and pepper. Reserve 1 cup white sauce.

2. Warm oil in large nonstick skillet over medium-high heat. Add chopped asparagus (not tips) and cook, stirring often, 5 minutes, or until tender. Add garlic; cook, stirring, 1 minute, and season to taste with salt and pepper. Remove from heat.

3. Coat 13x9-inch baking dish with cooking spray. Place layer of noodles in dish, overlapping slightly. Layer with half of cooked asparagus, 3/4 cup Fontina and half of sauce. Add another layer of pasta, remaining sauce, remaining cooked asparagus and 3/4 cup Fontina. Top with layer of noodles, then with reserved 1 cup white sauce. Arrange reserved asparagus tips over top and sprinkle with remaining Fontina.

4. Bake, uncovered, 35 to 40 minutes, or until golden. Let stand 10 minutes; serve with additional grated Parmesan cheese, if desired.