Preheat the oven to 375°F (190°C). Lightly grease a 9 × 13-inch baking dish.
Bring a large pot of salted water to a boil. Cook the pasta until 1–2 minutes shy of al dente. Drain well and set aside.
In a large bowl, combine the condensed cheddar soup, milk, sour cream, Dijon mustard, smoked paprika, onion powder, garlic powder, oregano, and salt. Whisk until smooth and creamy.
Place in the prepared baking dish; the cooked pasta, the cooked shredded chicken, the broccoli florets, and 1 cup of the grated cheddar cheese. Stir around.
Pour the liquid mixture over the baking dish or ingredients. Stir until everything is coated and level the ingredients with a spatula. Sprinkle the remaining ½ cup of grated cheddar over the top.
In a small bowl, combine the panko, melted butter, and parsley. Sprinkle evenly over the casserole.
Bake for 20–25 minutes, or until bubbling around the edges and golden brown on top. Let rest for 5 minutes before serving.