01 - In a small mixing bowl, gently combine blueberries with honey and lemon zest if desired.
02 - Evenly spread the softened cream cheese on one side of each bread slice.
03 - Sprinkle shredded mozzarella cheese over the cream cheese on half of the bread slices.
04 - Spoon the blueberry mixture over the mozzarella, distributing it evenly across the slices.
05 - Top with the remaining bread slices, cream cheese side facing down, to form closed sandwiches.
06 - Spread softened butter evenly on the outer sides of each sandwich.
07 - Heat a nonstick skillet over medium heat. Place sandwiches in the skillet and toast for 3 to 4 minutes per side, pressing gently, until bread is golden brown and cheese is melted.
08 - Remove sandwiches from the skillet, allow to cool slightly, slice in half, and serve while warm.