Preheat oven to 350℉. Spray a wide, shallow baking dish with cooking spray.
In a large skillet heat oil over medium. Add kale and cook, stirring, until wilted. Transfer to a bowl and set aside.
In same skillet melt butter over medium heat. Add onion, salt, and pepper and sauté until softened, 6-8 minutes. Stir in flour, then gradually stir in cream and broth. Bring to a simmer and cook until thickened. Take off heat and stir in cheese.
In prepared baking dish arrange kale and squash and pour cheese sauce over everything.
Cover with foil and bake until squash is tender and sauce is thick and bubbly, about 40 minutes.
In a small bowl stir together panko and Parmesan. Remove foil from baking dish and sprinkle panko mixture over it. Return to oven and bake until browned, about 15 minutes. If desired, broil briefly to brown.
Let cool for 10 minutes before serving.