Yummy Leftovers

Several nights ago I made spaghetti for dinner and ate the leftovers for lunch the next two days. The sauce out-lasted the pasta.
Meanwhile, I had sauteed some sliced summer squashes (zucchini, yellow and a small speckled pale green squash) with some chopped onion (first in the pan) and chopped roma tomatoes (added at the very end to just warm them). This was all cooked in olive oil. After dinner there was still some left so I put it in a plastic container with the leftover sliced green onions from the baked potatoes.
Two days later I thought, why don't I mix that with the extra spaghetti sauce and have that for lunch. I just mixed it together in a bowl, heated it in the microwave and threw on a little grated cheese at the end.
This was so good, I may end up making it deliberately for dinner soon.

By the way, I don't really have a recipe for spaghetti sauce but this is my formula:
Heat up a large fry pan on the stove. If you are using meat (I usually use plain old ground beef, if I am) start cooking it breaking it up into small pieces as you brown it. Meanwhile, chop about half an onion and fresh mushrooms, if they are on hand. Saute with olive oil or in the fat from the meat in the same pan. Add a spoonful of garlic from that jar in the refrigerator or a clove or two of fresh garlic, chopped, just as the onions are getting translucent.
Add a can or two of diced tomatoes, some tomato sauce and/or paste. What you add here depends on what you have and how much you are making. Add some oregano and basil. A dash of red wine is nice, if you have it. We usually don't. Sometimes I add a little (1 tablespoon?) sugar. Taste it first.
Let this all simmer while the spaghetti cooks. Stir occasionally.
Nothing fancy or authentic but it is a tasty sauce that everyone likes and it can be adjusted to fit what is on hand and what your personal tastes are.