Pizza Casserole

1 pound ground beef
1/3 cup onion
1 - 15 ounce jar spaghetti sauce
1 egg
1 cup milk
1 cup bisquick
8 ounces mozzarella cheese
1/3 cup parmesan cheese
1 tablespoon oil
1 teaspoon salt

Brown ground beef and drain. Pour meat into casserole dish. Add onion and spaghetti sauce. In a seperate bolw add egg, milk, oil and Bisquick. Mix well. Pour mixture over ground beef. Bake at 350 degrees for 25 to 30 minutes. Bisquick mix should be brown. Add cheesese on top and bake another 5 minutes or until cheese is melted.