Hamburger Stroganoff

Ingredients

• one half pound lean ground beef
• 1 tablespoon butter or margarine
• 1 can (4 ounces) sliced mushrooms, drained
• 2 tablespoons chopped onion
• 2 tablespoons flour
• one and one half cups beef broth
• one half teaspoon salt
• dash pepper
• 1 tablespoon ketchup
• one half cup sour cream
• 3 quarts boiling water
• 8 ounces (4 cups) rigatoni macaroni
• minced parsley