Preheat oven to 350 degrees and butter a large baking dish.
Cook the pasta according to the package directions, drain and reserve.
Melt 3 tbsp butter in a large skillet over medium heat, add the onion and garlic and sauté until soft and translucent. Stir in the chicken and hot sauce and cook two-three minutes until it is warmed through and well mixed.
In a saucepan, melt 2 tbsp butter over medium heat. Add the flour and mustard and stir until it forms a smooth paste. Slowly whisk in the half and half and remaining ¼ cup of hot sauce and continue to stir constantly until the mixture is thick. (2-5 minutes). Stir in the cheeses by handfuls and continue to stir until the cheese has all melted and the sauce is smooth.
In your baking dish, mix together the pasta and chicken, then pour the cheese sauce evenly over the whole thing.
Melt 2 tbsp butter and stir it together with the panko, blue cheese and parsley.
Sprinkle the topping over the macaroni and cheese mixture.
Cook 30-40 minutes until hot and bubbly. Let it rest for 10 minutes or so before cutting into it.
Recipe Notes
Macaroni and cheese can be prepared a day or two in advance. Refrigerate until needed and adjust the cook time by adding an extra 30 minutes if cooking from cold. Cover it with foil for the first 30 minutes of cooking time.