Spread margarine on one side of each slice of bread. On 2 bread slices, margarine side down, layer cheese, tomato slices and another slice of cheese. Top with remaining bread slices, margarine side up.
Heat large skillet over medium heat until hot. Add sandwiches; cook 2 to 3 minutes or until golden brown. Turn; cover and cook 2 to 3 minutes longer or until golden brown and cheese is melted.