Cook ½ cup uncooked quinoa according to package directions; fluff with a fork and set aside.
Preheat your oven broiler (high) and position the oven rack about 6 inches below the broiler element.
In a large oven-safe skillet over medium heat, melt 1 tablespoon unsalted butter.
Add ⅓ cup finely chopped red bell pepper, 1 cup roughly chopped artichoke hearts, and 2 cups roughly chopped fresh spinach to the skillet. Cook, stirring occasionally, until the spinach is wilted and the peppers have softened.
Sprinkle in 2 tablespoons all-purpose flour and cook, stirring frequently, for 1–2 minutes.
Gradually whisk in 1 ¾ cups milk until smooth. Add 1 teaspoon chicken bouillon powder, ¾ teaspoon Italian seasoning, ¾ teaspoon onion powder, ½ teaspoon garlic powder, and black pepper to taste. Stir to combine.
Bring the mixture to a gentle simmer and cook, stirring occasionally, until the sauce is thickened and creamy.
Reduce heat to low and stir in ¼ cup plain Greek yogurt, 1 ½–2 cups shredded cooked chicken, ¾ cup shredded Italian cheese blend, and the cooked quinoa. Stir until everything is well combined and the cheese is melted.
In a small bowl, mix ½ cup Panko bread crumbs, ½ teaspoon dried parsley, ½ teaspoon garlic seasoning (or ¼ teaspoon garlic powder), and 1 tablespoon melted butter until the crumbs are evenly coated.
Evenly sprinkle the breadcrumb mixture over the top of the skillet mixture.
Place the skillet under the preheated broiler and broil for a few minutes, watching closely, until the breadcrumbs are toasted and golden. Remove from the oven and serve.