Kale and Artichoke Chicken Casserole

Name: Kale and Artichoke Chicken Casserole
Ingredients: 2 bunches kale, tough center stems removed, chopped into 2-inch pieces; 2 to 3 tablespoons extra-virgin olive oil; 1 pound boneless, skinless chicken breasts, cut into 1/2-inch pieces; Kosher salt and freshly ground black pepper; 1 small onion, finely chopped; 2 tablespoons all-purpose flour; 3/4 cup 2 percent milk; 1 cup low-sodium chicken broth; 8 ounces frozen artichoke hearts, thawed and roughly chopped; 1/4 teaspoon cayenne; 4 tablespoons grated Parmesan; Nonstick cooking spray, for spraying the baking dish; 2 tablespoons panko breadcrumbs