One thing I think you need to know how to do, to make the most out of what's on hand for cooking, is figure out how to cook or bake things in different proportions, according to what you have and the number of people eating. Today's example: I had leftover mashed potatoes and thought of making a Perogy Casserole. There were about seven lasagna noodles, plus some broken pieces, in the cupboard. But my recipe makes a 9 x 13 inch panful and calls for fifteen noodles. Since that usually leaves us with leftovers, I figured it would work just as well to cook up what we had and use a smaller pan. I didn't even bother reducing the rest of the ingredients; I wanted to use up the potatoes and I figured nobody would complain about a bit of extra filling.
Perogy Casserole, made with somewhere between seven and eight lasagna noodles
Meat and Vegetable Reheat: that is, a bit of sliced leftover beef from last night; a package of mushrooms, sliced; some leftover green beans; a cupful of beef broth; and a teaspoonful of smoked paprika, heated through in a covered skillet and thickened at the end with a spoonful of cornstarch. (Wow, does that make an awesome mushroom sauce--I think it's the combination of the mushroom liquid, the broth, and the paprika.)
Lettuce, carrot and celery salad
Dessert: this and that.