Chicken Spaghetti Casserole

Name: Chicken Spaghetti Casserole
Ingredients: 1 pound spaghetti; 4 tablespoons (½ stick) salted butter; ¼ cup all-purpose flour; 2 ½ cups whole milk; 12 ounces Asiago cheese, shredded (about 4½ cups); 1 teaspoon kosher salt; 3 cups shredded rotisserie chicken (10 oz.); 3 tablespoons finely chopped fresh basil, plus more for serving; 3 tablespoons finely chopped fresh flat-leaf parsley, plus more for serving; 3 tablespoons finely chopped fresh chives, plus more for serving; 1 tablespoon fresh lemon juice (from 1 lemon)