#1. Heat Andouille Sausage in a skillet for 8-10 minutes until heated through. Remove the sausage from the skillet, and set aside. #2. Boil salted water and stir in macaroni according to box instructions. Cook until Al dente (firm but not hard). #3. Preheat an oven to 350°F. Grease a 9x13 inch baking dish. #4. Melt the butter in the skillet over medium-low heat, and cook and stir the chopped onion for about 5 minutes, until translucent. Whisk in the flour, stirring constantly to avoid lumps. Cook and stir the butter, onion and flour for 2 to 3 minutes to make a roux, and remove from the heat. Whisk in the milk and cream a little at a time, stirring constantly, until all has been incorporated, and return to low heat. Bring the sauce to a simmer, and cook over low heat for about 2 minutes, stirring constantly, to finish cooking the flour. Whisk in the Cheddar cheese until is incorporated and the sauce is hot and smooth. #5. Pour the macaroni into the cheese sauce, and stir to combine. Add in the Sausage, cayenne pepper, salt, and black pepper. #6. Spoon the macaroni mixture into the prepared baking dish, and sprinkle the bread crumbs over the top. Bake for about 20 minutes in the preheated oven, until the crumbs are brown and bubbling. Let stand for 15 minutes after baking, to set before serving.