Prepare lasagna according to package direction directions. Drain and return to pan. (Gently mix in a little butter so it doesnt stick together.) Set aside. Squeeze sausage out of its casing into large frying pan and cook about 5 minutes, stirring to break up. Drain excess fat if necessary. Add onion and garlic and cook 5 more minutes or until onion is soft, stirring frequently. Set aside. If cooking lasagna right away, heat sauce until it simmers. Remove from heat and set aside. If making ahead and the lasagna will be refrigerated, leave the sauce cold. (Save a 1-1/2 cups of sauce for serving with finished lasagna because in case it gets a little dry.) Combine egg, ricotta, parsley stirring well. Set aside. Spray 13x18 inch lasagna pan with vegetable oil spray. Spoon about 2 cups sauce in bottom of pan. Layer 1/3 noodles (cut to fit if necessary), then 1/3 sauce, 1/3 sausage, 1/3 ricotta, 1/3 olives, 1/3 the mozzarella and 1/3 the parmesan. Repeat layering ending with the parmesan. Cover with foil. (May be refrigerated at this point.) Bake in a 375 degree oven for 25 minutes (40 if it was refrigerated). Remove foil and bake uncovered 25 minutes longer. Lasagna should be bubbling around edges and lightly browned. Let stand 10 minutes before cutting otherwise it will be a mess when serving. Makes 12 to 18 servings depending on how it is cut and served.