The squash and carrots are optional in this recipe, but I like the contrast of color and the flavors they pick up in the sauce. You may be tempted to substitute white wine or even sherry, but the resulting flavors will not define a true Marsala dish. Buy a drinkable Marsala (around $10) not a bottle marked “cooking wine.” An opened bottle of Marsala will last a year or so; you’ll find many recipes to use the leftover wine. Some cooks like to add cream to this dish, but I urge you to stick with this pan sauce reduction and experience its intensity. If you make your chicken stock from bones, you may not need the gelatin; gelatin gives the sauce a thick, velvety texture that is the signature of a glaze-like Marsala sauce. You could serve this dish with a side of rice, mashed potatoes, or even stone-ground grits, but staying with tradition, it’s time to use your noodle—linguine, that is.