In a large deep pan over high heat, bring water to a boil. Gradually stir in the grits. Reduce heat and simmer gently, stirring frequently to prevent sticking, until mixture is very thick (about 30 minutes). Use a long-handled spoon because the mixture pops and bubbles and can burn.
If using, stir in 3 tablespoons butter and add salt if needed. Stir in cheddar cheese until melted. Pour mixture into a greased loaf pan and chill overnight.
Slice to the desired thickness and fry in a hot pan, using a small amount of oil, for 4 - 5 minutes each side.
