I like to keep plenty of jars of pasta sauce in my food cupboard, even though I rarely eat pasta. (The basic 'value' ones are fine. Even though their website incorrectly says that they no longer stock it, Morrisons sell their 'Savers' one for 39p. Lidl have a range of six different types at 49p). It makes a great starting point for all sorts of dishes, including chilli dishes, curries, casseroles and lots more. I simply throw in whatever I think that it needs to achieve the right result. (I usually get three portions from a single jar but with some dishes I can stretch that to four portions).
A particular favourite of mine is a portion of diced chicken breast placed in a casserole dish, with pasta sauce poured over the top and some slices of cheddar cheese on top. Cook for 30 minutes at Gas Mark 6 (200C) and serve with a buttered jacket potato. (Something like broccoli really tops it off but I often don't bother with it).
Pasta sauces are usually much cheaper than proper 'cook in' sauces but they're just as good and, because one can then add in what one likes, far more versatile too.