Preheat the oven to 350ºF. Spray a 9x13-inch casserole dish with nonstick cooking spray and set to the side.
Bring a large pot of water to a boil, then salt generously. Add the pasta and cook until al dente. Drain, then return to the large pot.
While the pasta is cooking, melt 3 tablespoons of the butter in a large skillet over medium-high heat. Add the onion and cook until soft and translucent, about 5 minutes. Stir in the garlic and cook until fragrant, about 30 seconds. Add the chicken and 1/2 cup of the hot sauce and cook until heated through.
In a a saucepan, melt 2 tablespoons of the butter over medium heat. Whisk in the flour and the mustard powder and cook for a minute or two. Whisk in the half and half, then add the remaining 1/4 cup of hot sauce. Cook until the mixture is thick, about 2 minutes. Whisk in the cheddar cheese and the pepper jack cheese, then stir in the sour cream.
Add the chicken mixture and the cheese mixture to the cooked pasta in the large pot. Stir until completely combined. Pour into the prepared casserole dish.
Melt the remaining 2 tablespoons of butter. Stir in the panko breadcrumbs until coated, then stir in the blue cheese and the parsley. Sprinkle the mixture over the pasta in the casserole dish.
Transfer to the oven and bake until bubbly, about 30-40 minutes. Let the macaroni sit for 10 minutes before serving.
Notes
slightly adapted from Food Network Magazine April 2010SUBSTITUTIONS: I have only used elbow macaroni, but any short cut pasta should work.If you don’t have cooked, shredded chicken on hand, a rotisserie chicken is an easy substitution.FREEZE: This recipe should freeze well. Just make sure to cook your pasta to al dente - don’t take it too far or it will be too soft when defrosted. Once the casserole is assembled, let it come to room temperature and wrap tightly, label, and freeze. It can be frozen for up to 6 months.The best way to defrost is in the refrigerator overnight. Then before serving, bake at 350ºF for about 40-50 minutes.STORE: Store any leftovers in the refrigerator for 3-5 days. You can reheat in the oven (covered with foil) or you can reheat individual portions in the microwave. I do find that it will dry out a bit as leftovers, though.Nutrition information provided as an estimate only. Various brands and products can change the counts. Any nutritional information should be used as a general guide.