Step 1 Heat the oven to 350 degrees. Cook the macaroni in plenty of rapidly boiling salted water until done, about 10 minutes. Drain well and set aside.
Step 2 Melt the butter and saute the onion and garlic until soft, about 5 minutes. Whisk in the flour to make a roux. Cook until mixture is smooth, about 5 minutes. Whisk in the milk and the cream and simmer until the mixture is thick and creamy, about 15 minutes.
Step 3Add the garlic, mustard, Jack, 1 cup of Cheddar, Parmesan and 1/2 cup blue cheese. Return to the heat till melted. Add a dash of hot sauce and salt and pepper to taste.
Step 4Mix the sauce with the cooked macaroni and put in a 13x9-inch baking dish. Sprinkle the reserved 1/2 cup of Cheddar and 1/4 cup blue cheese on top and bake until brown and crusty on top, about 30 minutes.