In a small bowl, whisk together balsamic vinegar, garlic powder, honey, oil, and Italian seasoning and season with salt and pepper. Pour over chicken and marinate 20 minutes.
3/4 c. balsamic vinegar, 1 tsp. garlic powder, 2 tbsp. honey, 2 tsp. Italian seasoning, 4 boneless skinless chicken breasts, Freshly ground black pepper
When ready to grill, heat grill to medium-high. Oil grates and grill chicken until charred and cooked through, 8 minutes per side.
Top chicken with mozzarella, avocado, and tomato and cover grill to melt, 2 minutes.
4 slices avocado, 4 slices tomato, 4 slices mozzarella
Garnish with basil and drizzle with balsamic glaze. 2 tbsp. Freshly sliced basil, for garnish