Transfer the browned beef and softened onion mixture from the skillet into the slow cooker crock. Pour both cans of tomato sauce over the top and stir everything together thoroughly until the beef and onion are evenly coated and distributed through the sauce. If you prefer a looser, more liquid consistency in the finished dish, stir in up to 1 cup of water at this point. Sprinkle in the salt and black pepper if using, stir again, and taste the sauce carefully — bearing in mind it will be very hot. Adjust seasoning as needed, remembering that the flavors will deepen and concentrate considerably during the cooking process.
Step 4: Slow Cook the Base
Place the lid on the slow cooker and set it to cook on LOW for 4 to 5 hours or on HIGH for 2 to 3 hours. This initial cooking period allows the beef and onion to fully integrate with the tomato sauce, the flavors to meld and deepen, and the onion pieces to become completely soft and tender. The house will fill with the most wonderful savory aroma as it cooks — the same smell that told my grandfather's family that something good was almost ready.
Step 5: Add the Macaroni
Approximately 30 to 40 minutes before you plan to serve the meal, open the slow cooker and stir in the dry elbow macaroni. Make sure all the pasta is pushed down into the sauce so the noodles are fully submerged and can absorb the liquid evenly as they cook. If the mixture looks very thick at this point, add a splash of additional water — just enough to ensure the pasta has sufficient liquid to soften properly without leaving the dish watery. Stir well to distribute the pasta evenly throughout the sauce.
