Spray crockpot with cooking spray. Scrub about 3 medium russet potatoes and cut into small chunks, leaving the skin on. (If you cut the spuds into too large a size pieces, they will take too long to cook since everything else is basically done.) This made one layer on the bottom of my 5-quart crockpot. Season spuds with salt, pepper and garlic powder to your own taste. Brown 1 pound of ground beef with 1/2 chopped onion, drain fat. Put on top of spuds. Mix one can of Campbell's Cream of Mushroom soup with 1 tsp beef concentrate flavor. Drain two 14 or 15 ounce can of cut green beans and put in slow cooker. Cover and cook on high for 3 hours, stirring a couple of times. Turn to low and sprinkle shredded cheddar cheese on top of shepherd pie and cook for 30 minutes or so.