Preheat oven to 400°F.
Cook macaroni al dente in salted water according to package directions. Drain and run under cold water to stop the cooking.
While the macaroni is cooking, melt the butter in a saucepan over medium heat. Stir in flour, mustard powder and, onion powder and cook 1 minute.
Add milk and cream a little bit at a time whisking after each addition. The mixture will be very thick at first but will smooth out. Once combined bring to a boil while stirring and let boil 1 minute.
Remove from the heat and add Cabot Seriously Sharp Cheddar and Cabot pepper jack. Whisk until melted and smooth. Once melted, stir in the buffalo sauce.
Combine the cooked macaroni, chicken, and cheese mixture, mix well. Spread into a greased 9x13 pan.
Combine topping and sprinkle over the macaroni.
Bake 20-25 minutes or until bubbly and the topping is browned.
