Preheat the grill to medium-high heat.
Brush the chicken breasts with olive oil, then season both sides with garlic powder, onion powder, salt, and pepper.
Grill the chicken for 5–7 minutes per side, or until the internal temperature reaches 165°F.
In the last 2 minutes of grilling, top each chicken breast with mozzarella cheese and allow it to melt.
Remove chicken from the grill and immediately top with avocado slices, tomato slices, and fresh cilantro.
Drizzle with balsamic glaze and serve warm.