Preheat the oven to 375F and butter a casserole dish or baking pan.
In a blender or food processor, puree cottage cheese, milk, mustard, nutmeg, salt and pepper. Reserve 1/4 cup grated cheese for topping. In a large bowl, combine remaining grated cheese, milk mixture and uncooked pasta. Pour into the pan, cover tightly with foil and bake for 30 minutes.
Uncover the pan, stir, dot with butter and bake uncovered for another 30 minutes, stirring once or twice. If you like, sprinkle with a little more cheese and bake for another 15-20 minutes, or until the pasta is tender and you have a nice cheesy top crust. Let stand for 15 minutes before serving.