Chuckwagon cooking is part of Texas' cattle driving past. This dish would have originally been cooked in a cast iron Dutch oven over an open fire in a hole. Taken from The Texas Cowboy Cookbook by Robb Walsh.
Preheat oven to 350ºF. Remove any bad spots from potatoes and slice thinly (1/16 inch)
Butter a small Dutch oven or 8x8-inch baking dish and layer half potatoes on the bottom. Sprinkle 1 cup of cheese and chunks of remaining butter on the potatoes. Sprinkle with salt and pepper. Layer with other half of potatoes and onion slices. Add milk. Sprinkle more salt and pepper over the top.
Bake the potatoes, covered, for about 1 hour, or until very tender. Remove cover, sprinkle with remaining cheese. Bake, uncovered, for 30 minutes or until potatoes are browned.