01 - In a small mixing bowl, gently toss the blueberries with honey and add lemon zest if desired.
02 - Spread cream cheese evenly on one side of each slice of bread.
03 - Sprinkle shredded mozzarella over two slices, on top of the cream cheese, and distribute the blueberry mixture evenly.
04 - Top each layered slice with the remaining bread, placing the cream cheese side down to form two sandwiches.
05 - Spread softened butter on the outside of each sandwich.
06 - Heat a nonstick skillet over medium heat. Place sandwiches into the skillet and cook for 3 to 4 minutes per side, gently pressing, until the bread is golden and the cheese has melted.
07 - Remove from the skillet, allow to cool slightly, cut in half, and serve while warm.