I cook roast beef in a crock pot all the time. Most people that have eaten it love it, including my husband, the executive chef...I've never been quite sure what the difference IS between pot roast and an oven baked roast.
3 to 4 lbs roast (we like arm or shoulder roast, but chuck works too)
salt to taste
Pepper to taste
bay leaf (2 or 3, to taste)
garlic powder or salt (or garlic from a jar) to taste
4 or 5 Potatoes washed well and sliced in about 3/4 inch pieces
package of baby carrots
1 or 2 onions, sliced
Put potatoes, carrots and part of the onion ON THE BOTTOM OF THE CROCK POT.
Put roast on top of vegtables and season, top with bay leaf and remaining onion. Add 1 cup water.
Cover crock pot and cook on low heat about 8 hours (it will be VERY tender, probably fall apart.
IF you don't want to do it in the crock pot, I basically follow the same directions and bake it in the oven at 350 degrees for about 3 hours (until it is as done as you want it. I happen to like mine pretty well done.) I use a heavy roasting pan with a cover.
Hubby makes gravy from the drippings either way.