Lightly butter one side of each bread slice. Cover with the remaining bread slices, keeping the buttered side facing out. If making a grilled sandwich, spread a thin layer of softened butter on one side of each bread slice. Grill the sandwich (optional)Heat a grill pan, sandwich press or non-stick frying pan over a medium heat. If you'd like a toasted sandwich, lightly brush one side of each bread slice with olive oil or butter.