This is a layered slow cooker shepherd's pie from sandy. This version with ground beef is better known as a "Cottage pie. " The dish could also be made with ground lamb or minced leftover lamb. The simple layers are versatile. For a meatier casserole, use 1 1/2 to 2 pounds of ground beef, and the green beans may be replaced with frozen green beans, carrots, or corn. We used red skinned potatoes in the pictured dish. We cut them into 1/2 inch cubes and they were perfectly cooked after three hours on high. We also added extra chopped onions, about 1 cup. Serve this tasty all-in-one meal with biscuits or crusty bread.