Preheat oven to a high broil.
Add six cups of water to a large pot on high heat until boiling. Add the kale, reduce to medium-high heat and cook about 2 minutes until tender. Drain and dry the kale with paper towels.
In a large skillet, heat 2 tablespoons of oil on medium-high heat. Season the chicken with the salt and pepper, then add it to the skillet and cook, stirring occasionally, for 4 minutes until no longer pink. Set chicken aside in a medium bowl.
Reduce skillet to medium heat and add the onions. Cook about 4 minutes, stirring occasionally, until translucent, then sprinkle flour evenly over onions, then stir and cook for an additional minute.
Gradually add the milk, stirring constantly until flour is dissolved, then stir in the chicken broth.
Increase the heat to medium high and bring to a simmer, stirring frequently. Cook for 2-3 minutes until slightly reduced.
Add the kale, artichokes, cayenne, and chicken. Cook, 3-4 minutes until vegetables and chicken are hot, then mix in 3 tablespoons of the Parmesan cheese.
Spray an 8x8 baking dish with cooking spray and pour in the contents of the skillet. Top with the panko breadcrumbs and remaining 1 tablespoon Parmesan.
Broil in the oven on the top shelf until lightly browned, about 2 minutes.