Prick the potatoes with the tines of a fork and place in a baking dish. Roast until the potatoes are tender, about 45 minutes. Remove from the oven. When cool enough to handle, peel off the skin and place the flesh in a bowl. Mash with a hand masher. Add enough chicken broth to achieve desired consistency. Season with salt and pepper. Be careful adding salt as many chicken broths contain lots of salt already.