Cut corn from cob and put into 2 large roasting pans (should have 18-20 cups cut corn). Add butter or margarine and half-and-half. Place uncovered in 300-degree oven. Bake for 1 hour, stirring well every 15 minutes. Remove from oven and set pans in cold water to chill. (Be careful not to get water into corn). Package and freeze. When ready to use, heat and add salt and a little sugar to taste.