Cottage cheese lends a tanginess to the cheddar cheese sauce in this rendition of the well-loved side dish casserole. A Parmesan and crumb topping further enhances the cheesiness.
Heat oven to 350 F. Coat a 2-1/2- or 3-quart baking dish or six 10- to 12-ounce ramekins with nonstick cooking spray.
Cook pasta following package directions. Drain and return to the pot.
While the pasta cooks, combine milk and flour in a medium-size saucepan and whisk until smooth. Cook over medium heat, whisking constantly, until mixture comes to a boil and thickens slightly. Remove from heat and add cheddar cheese, whisking until smooth. Whisk in cottage cheese, dry mustard, cayenne and salt.
Stir cheese sauce into pasta. Gently fold in spinach in two additions.
Spoon mixture into the prepared baking dish. Stir together breadcrumbs and Parmesan cheese. Sprinkle on top.
Bake at 350 F for 25 to 30 minutes for large dish, 20 minutes for ramekins or until heated through. Remove from oven; let stand for 10 minutes before serving.