Preheat oven to 350 degrees. Brown ground beef, onion and pepper in saucepan. Cook until beef is done. Drain well.
Add tomato paste, tomato sauce, water, and dried Italian seasoning and stir well to blend.
Let simmer for 10 minutes.
Meanwhile, cook elbow macaroni as directed on package. While macaroni is cooking, combine cream cheese and milk in medium bowl. Cook in microwave on medium power for 2-3 minutes, stirring once halfway through cooking. Remove from microwave and stir with wire whisk until sauce is smooth.
Drain noodles and add to cream cheese sauce along with sour cream and 1/2 cup Parmesan cheese; stir.
In 2 quart casserole dish, place all of cream cheese mixture. Top with all of the ground beef mixture and sprinkle with remaining 1/4 cup Parmesan cheese.
Bake at 350 degrees for 20-30 minutes until casserole is bubbly.
To freeze, add 1 tablespoons cornstarch to the cream cheese sauce. Prepare casserole as directed, except instead of baking, chill in refrigerator. Wrap well and freeze up to 3 months.
To thaw and reheat, thaw casserole overnight in refrigerator.
Bake, covered, for 25-35 minutes 5 minutes longer until bubbly.