Ingredients

• 1 tablespoon olive oil
• 1 cup finely chopped shallots
• 1 tablespoon chopped fresh rosemary
• 2 cups sourdough croutons (see Caesar Salad recipeepi:recipelink), coarsely crumbled</epi:recipelink>
• 1/4 cup chopped fresh Italian parsley
• 1/4 cup all purpose flour
• 3/4 teaspoon cayenne pepper
• 1/2 teaspoon ground nutmeg
• 6 tablespoons (3/4 stick) butter
• 4 cups whole milk
• 3 cups (packed) coarsely grated extrasharp cheddar cheese, divided
• 3 cups (packed) coarsely grated Fontina cheese, divided
• 1/2 cup grated Pecorino Romano cheese, divided
• 8 cups reserved cooked ziti
• Chopped fresh Italian parsley

Instructions

1. Heat oil in skillet over medium-high heat. Add shallots and rosemary; sauté 5 minutes. Mix in croutons. Cool; stir in parsley.
2. For mac and cheese: Preheat oven to 375°F. Butter 13 x 9 x 2-inch glass baking dish. Whisk flour, cayenne, and nutmeg in small bowl. Melt butter in heavy large pot over medium-high heat. Add flour mixture; stir 1 minute (do not brown). Gradually whisk in milk and bring to simmer. Cook until sauce thickens, 4 to 5 minutes. Whisk 2 cups cheddar, 2 cups Fontina, and 1/4 cup Pecorino Romano into sauce. Season generously with salt and pepper. Stir in pasta; remove from heat. Mix 1 cup cheddar, 1 cup Fontina, and 1/4 cup Pecorino Romano in small bowl. Layer half of pasta mixture, then cheese mixture in baking dish; repeat. Sprinkle with breadcrumb topping. Cover with foil. Bake 30 minutes. Uncover and bake until topping is golden, 10 to 12 minutes. Top with chopped parsley.
3. Preheat oven to 375°F. Butter 13 x 9 x 2-inch glass baking dish. Whisk flour, cayenne, and nutmeg in small bowl. Melt butter in heavy large pot over medium-high heat. Add flour mixture; stir 1 minute (do not brown). Gradually whisk in milk and bring to simmer. Cook until sauce thickens, 4 to 5 minutes. Whisk 2 cups cheddar, 2 cups Fontina, and 1/4 cup Pecorino Romano into sauce. Season generously with salt and pepper. Stir in pasta; remove from heat. Mix 1 cup cheddar, 1 cup Fontina, and 1/4 cup Pecorino Romano in small bowl. Layer half of pasta mixture, then cheese mixture in baking dish; repeat. Sprinkle with breadcrumb topping. Cover with foil. Bake 30 minutes. Uncover and bake until topping is golden, 10 to 12 minutes. Top with chopped parsley.