Delicata Squash Lasagna

Name: Delicata Squash Lasagna
Ingredients: 5 tablespoons butter; 5 tablespoons flour; 5 cups milk; Kosher salt; Ground black pepper; Ground nutmeg; 1 3/4 pounds delicata squash, 2-3 small; 1 box oven ready lasagna; 15 ounces ricotta, fresh or container; 5 ounces arugula, about 4 cups; 2 cups shredded goat gouda cheese, about 8 oz; Scallions, garnish