Cook macaroni according to package directions.
In a Dutch oven or large pot, melt butter over medium heat.
Add onion and cook until translucent, about 2 minutes
Add flour, stir and cook 1-2 minutes to get “floury” taste out
Gradually whisk in half and half. Bring to a simmer. Add salt, pepper, garlic powder, onion powder, and dry mustard.
Once thickened, turn heat to low and add cream cheese. Stir until melted.
Add Monterey Jack cheese and cheddar cheese. Stir until melted.
Stir in sour cream and hot sauce.
Add macaroni and chicken to pot with cheese sauce. Stir to combine.
Top with blue cheese crumbles and drizzle with additional hot sauce if desired.