Dan Dan Noodles!
Dan Dan noodles is my current favorite frugal meal. (Someone will correct my inauthentic American Dan Dan, but here it goes)
Make the cheapest spaghetti / egg noodles you can find. Get a quarter cup of the boiling noodle water and add a enough peanut butter and soy sauce to make a thin sauce. Top off the noodles with chopped peanuts and minced garlic. It warms the soul and the peanut fats will keep you full longer than spaghetti sauce.