This is a very rich and creamy, non-tomatoey, (even though it includes some tomato), baked spaghetti. It's my most-requested recipe from friends. I gave the ingredients a lot of thought before preparing it the first time and it came out just right -- I've never changed it over the two years I've been making it. Reasonable substitutions won't hurt this recipe -- use what you have. This is a simple recipe and most beginners can easily prepare it.