01 - In a small mixing bowl, gently combine the fresh blueberries with honey and optional lemon zest.
02 - Evenly spread softened cream cheese on one side of each slice of bread using a butter knife.
03 - Distribute the shredded mozzarella evenly over half of the slices, on top of the cream cheese layer.
04 - Spoon the blueberry mixture onto the mozzarella layer and top each with a remaining bread slice, cream cheese side down, forming sandwiches.
05 - Spread softened butter on the outer sides of each sandwich for golden toasting.
06 - Heat a nonstick skillet over medium heat. Place sandwiches in the skillet and toast for 3–4 minutes per side, pressing gently, until the bread is golden and the cheese has melted.
07 - Remove sandwiches from the skillet, let cool briefly, slice in half, and serve warm.