Cauliflower Mac and Cheese

Bring a large pot of water to a boil and generously season with salt. Add cauliflower florets and simmer for 12 minutes until tender. Meanwhile, bring an 8-quart stock pot of water to a boil and generously season with salt. Cook pasta according to al dente package instructions. Reserve 1/2 cup pasta water and drain pasta. Place a large sauté pan over medium heat and add 2 tablespoons butter. When butter is melted stir in 1/4 teaspoon salt and breadcrumbs. Toast breadcrumbs until golden brown. Transfer to a bowl, mix with parsley and set aside. In the same sauté pan melt remaining 3 tablespoons butter over medium heat. When butter begins to bubble, add flour and whisk constantly until well incorporated, about 2 minutes. Season with 1/2 teaspoon each salt and black pepper. Whisk in milk and add cauliflower using a slotted spoon; bring to a boil and mash cauliflower. Stir in Parmesan and drained pasta. Add additional pasta water if the sauce is too thick. Turn off heat and top with torn mozzarella. The heat of the pasta will melt the cheese. Top with breadcrumb mixture and freshly grated parmesan. Serve immediately.