Preheat the Pan: Place a non-stick skillet or griddle over medium heat to preheat while you assemble the sandwich.
Butter the Bread: Spread the softened butter evenly on one side of each slice of bread.
Layer the Cheese: Place one slice of cheese on the unbuttered side of one slice of bread. Add any optional toppings, if desired, such as sliced tomato or cooked bacon.
Top with Second Slice of Bread: Place the second slice of bread on top of the toppings, with the buttered side facing up.
Grill the Sandwich: Carefully place the assembled sandwich, buttered side down, onto the preheated skillet or griddle. Cook for 2-3 minutes, until the bottom is golden brown and crispy.
Flip and Cook the Other Side: Using a spatula, carefully flip the sandwich over and continue cooking for another 2-3 minutes, until the second side is golden brown and the cheese is melted.
Serve: Remove the grilled cheese sandwich from the skillet or griddle and transfer it to a plate. Allow it to cool for a minute or two before slicing in half and serving.
