1. 1. Preheat the oven to 375°F (190°C).

2. 2. Slice the eggplant and sweet pepper into thin slices.

3. 3. In a baking dish, layer the sliced eggplant, sweet pepper, diced tomatoes, and shredded mozzarella cheese.

4. 4. Repeat the layers until all ingredients are used up, ending with a layer of shredded mozzarella cheese on top.

5. 5. Cover the baking dish with foil and bake for 30 minutes.

6. 6. Remove the foil and bake for an additional 15 minutes until the cheese is melted and bubbly.

7. 7. Let it cool slightly before serving.