01 - In a small mixing bowl, gently combine fresh blueberries with honey and lemon zest, if using.
02 - Evenly spread cream cheese on one side of each bread slice using a butter knife.
03 - Sprinkle shredded mozzarella evenly over two bread slices, directly atop the cream cheese.
04 - Distribute the blueberry mixture evenly over the cheese-covered slices.
05 - Place remaining bread slices, cream cheese side down, to create sandwiches.
06 - Spread softened butter on the outer sides of each sandwich.
07 - Heat a nonstick skillet over medium heat. Place sandwiches in the skillet and toast each side for 3 to 4 minutes, pressing lightly, until golden and the cheese is melted.
08 - Remove sandwiches from the skillet, let cool slightly, slice in half, and serve warm.