Potato Onion Au Gratin

Preheat the oven to 350 degrees. Grease the inside of a 9x13 inch baking dish. Melt the butter in a medium skillet over medium heat. Add the onion and cook about 10 minutes until tender, stirring occasionally. Alternate layers of potat, onion and cheddar in the prepared dish. Season with salt and pepper. Pour the broth over the layers. Cover the dish tightly with foil and bake about 60 minutes until the potatoes are tender. Uncover the dish and continue baking 15 to 20 minutes until the top is lightly browned. Serve hot.