- Preheat oven to 375º. Lightly grease a 9x13 inch baking dish.
- Bring a large pot of lightly salted water to a boil. Add pasta and cook for 8 to 10 minutes or until tender; drain.
- Melt butter in large saucepan over medium heat. Stir in the onion, and cook for 3 minutes until it begins to soften.
- Add the garlic, and continue cooking until the onion has softened and turned translucent, about 2 minutes more.
- Slowly stir in the flour, and cook, stirring constantly for 5 minutes.
- Stir in the half-and-half and milk, and bring to a simmer. Reduce heat to medium-low and stir in mustard powder and simmer for 10 minutes, stirring occasionally.
- Add 1 cup of Parmesan cheese, along with cream cheese, Velveeta cheese, Swiss, Monterey Jack, and Cheddar cheeses; stir until melted.
- Season to taste with salt and pepper, then stir in the drained macaroni noodles.
- Pour into the prepared baking dish. Sprinkle the remaining 1/2 cup of Parmesan cheese and breadcrumbs over the macaroni
- Bake in preheated oven until bubbly and brown, about 30 minutes. Remove from the oven and allow to stand 5 to 10 minutes before serving.