Preheat your grill to medium-high heat.
Brush both sides of the eggplant slices generously with olive oil and season with salt and pepper.
Place the eggplant slices on the hot grill and cook for 3-4 minutes per side, or until tender and lightly charred with grill marks.
If desired, you can also lightly grill the tomato slices for 30-45 seconds per side to soften them slightly and enhance their sweetness.
On a serving platter, arrange alternating layers of grilled eggplant, tomato slices, and mozzarella slices.
Sprinkle generously with fresh basil leaves, and drizzle with balsamic glaze or reduction (optional). Serve immediately.