Spread about 1 tablespoon butter into the bottom of a large skillet (or just leave some fat in the pan from the bacon). Spread 1 tablespoon (can use more) onto one side of each slice of bread. Place the 4 slices of bread butter-side down onto a large skillet or flat grill. Top with 1 slice of cheese, 2 slices of tomato and 2 slices cooked bacon, then 1 more slice of cheese. Cover with a slice of bread (butter-side facing outside). Fry over medium turning once with a spatula until golden brown on both sides.