Place potatoes in a greased 9x13 inch pan. Season with salt and pepper. Melt butter in the microwave. In a bowl add minced onions, sour cream, and cream of chicken soup, and melted butter. Mix these items together. Pour soup mixture over potatoes; sprinkle with Cheddar Cheese. Bake at 350 degrees for 45 minutes, or until all is completely warm, and the cheese begins to melt.