Preheat the oven to 325 degrees F (165 degrees C).
In a medium bowl, stir together the flour, salt and sugar. Pour in milk, eggs and cream, and stir into a smooth batter. Meanwhile, melt margarine in a cast iron skillet. Pour the batter over the melted margarine.
Place the skillet in the oven, and bake for 35 minutes. The pancake will rise to form a bubble in the middle. Remove from the oven, and let cool until the pancake sets, or goes down. Cut into pieces, serve with maple syrup and enjoy!