Preheat the oven to 350 degrees F.
Cook the pasta according to package directions; drain and set aside. While pasta is cooking, in a heavy, medium saucepan, combine the milk, clove-studded onion, thyme, and bay leaf over medium heat. In a large saucepan, heat the butter over medium heat. Add the diced onion and carrot and saute until tender. Add the flour and cook for 2 to 3 minutes. Strain the milk mixture into the flour mixture and stir until it's thickened and smooth. Strain this milk mixture into a heat-proof bowl. Stir in the shredded cheeses and mix until melted. Season, to taste, with salt, white pepper, and nutmeg. Stir in the pasta and mix well. Pour the macaroni and cheese into a baking pan and top it with the Bread Crumb Topping. Bake the macaroni and cheese until it is warmed through. Serve immediately.
In a small bowl, combine all ingredients and mix well.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.