Scalloped Potatoes

4 cups sliced raw potatoes
1 can Cream of Mushroom soup
1/4 cup milk
1 teaspoon salt
1/8 teaspoon pepper
2 tablespoons finely chopped onion
8 ounces shredded sharp Cheddar cheese
1 Tablespoon butter
PREPARATION:
Place half the potatoes in a greased baking dish. Sprinkle with half the salt, pepper, onion, and cheese. Dot with bits of butter. Repeat layer then combine soup and milk, then pour over potatoes. Cover with foil or lid and bake at 350° for 30 to 40 minutes, or until tender.
Take the lid off near the end of cooking to brown, or put under broiler for a few minutes. Serves 4 to 6.