Preheat oven to 350 degrees. Cook ziti according to pkg directions, drain. In skillet, heat oil. Then add and cook sausage 10 minutes. brown on all sides. Remove.
Sauce: In saucepan melt butter, remove from heat, add and stir flour, salt, and pepper until smooth. Gradually stir in milk. Then when smooth, bring to a boil over moderate high heat, stir constantly. Remove from heat when thickened and add 1/4 c. parmesan.
Put drained ziti in bowl and pour on cheese sauce and toss. Cut sausage diagonally into 1/2 inch thick slices, set aside.
Make cheese layer. Mix cottage cheese with 1/4 c parmesan, egg, parsley, salt, and pepper. mix well. Spoon 1/2 ziti macaroni-cheese-sauce mixture into 2 1/2 quart casserole dish.
Spread cottage-cheese mixture on top, and then spoon on remaining macaroni mixture. Arrange sliced sausage on top, tuck the slices partly under the macaroni. Sprinkle top with grated mozzarella and paprika.
Bake 30 - 35 minutes until cheese is melted and macaroni mixture is hot and bubbly. Let stand 5 minutes to set before serving. Makes 6 servings.