Arrange the cherry tomatoes and mozzarella balls nearby to prepare for assembly.
Using a small knife, carefully cut a tiny hole in the top of each mozzarella ball to create an opening for the basil and tomato.
Slide a small basil leaf into each mozzarella hole to resemble an iris, pressing gently to secure it.
Place a cherry tomato atop the mozzarella, pressing slightly to help it sit securely and mimic the red part of an eyeball.
Use a small skewer or toothpick to secure the cherry tomato to the mozzarella, ensuring the 'eyeball' stays together.
Arrange all the finished eyeball bites on a serving platter, spacing them evenly for a spooky effect.
Drizzle the balsamic glaze over the eyeballs for a gory, blood-like effect, completing the spooky look.
Serve immediately to keep the mozzarella firm and the basil fresh, or refrigerate briefly before serving.