Preheat oven to 400°F (200°C). Line two baking sheets with parchment paper.
- Brush eggplant slices with olive oil on both sides and season with salt and pepper. Arrange on baking sheets in a single layer.
- Roast for 15–20 minutes, flipping halfway through, until tender and lightly browned. Let cool slightly.
- In a bowl, mix ricotta, spinach, garlic, Parmesan, egg, salt, and pepper until smooth.
- Spread a spoonful of filling onto each eggplant slice and roll up from the short end.
- Spread a thin layer of marinara sauce in a baking dish. Place roll-ups seam-side down in the dish. Top with remaining marinara sauce and sprinkle with mozzarella.
- Bake for 20–25 minutes, until cheese is melted and bubbly. Garnish with fresh basil or parsley and serve warm.