Heat the grill. Lightly grill the bacon, if used. Slice the tomatoes, if used. Slice the cheese, making enough slices to cover the pieces of bread. Toast the bread lightly on both sides and spread one side with the butter. Arrange the slices of cheese on the buttered side of the toast and put under the grill for 1-2 minutes, until the cheese begins to bubble. Top with the tomato slices, bacon, or pickle and return to the grill for another minute, to heat the topping and brown the cheese. Eat at once.