I do mine overnight in the crockpot, along with some onions, dry sherry, garlic and beef base (the kind in the jar.) When it's falling apart, I take it out, shred it, de-fat the stock and marinate it in that. Freeze it in pint containers, whatever we didn't eat at dinner. Instant French dip. I did do it in the oven like that, but discovered I get the same result in the crockpot. Either way, the kitchen smells mighty good the next morning.