Slow cooking but quick to prepare spaghetti sauce. Let it simmer all afternoon but speed through the prep work by chopping all the veggies in the food processor. Makes a huge batch to fill your freezer.
Alternately, you could use a large crockpot. If you do this, then add the browned and drained beef to the crockpot and use that frying pan to sautee the vegetables before adding those to the crockpot as well.