Boil the potatoes whole, skins on, until tender. Peel while still hot and mash on a work surface. Season with salt and allow to cool slightly. Add the egg and flour and gently form a soft dough. Shape into finger-thick ropes and cut into ¾-inch pieces. Roll over a fork or gnocchi board if desired.

For the sauce, sauté the garlic clove in olive oil over medium heat. Add the tomatoes and simmer gently for 15 minutes. Remove the garlic, season with salt, and stir in fresh basil.

Cube the mozzarella and let it drain for 10 minutes. Grate the hard cheese.

Slice the eggplant into ¼-inch rounds, dredge lightly in flour, and fry until golden. Drain on paper towels.

Optional variation: eggplant can also be grilled or oven-roasted.

Cook the gnocchi in generously salted boiling water. When they float, remove with a slotted spoon and drain briefly.

Line a baking dish with eggplant slices. Add the gnocchi, cover with tomato sauce, scatter with mozzarella, and finish with grated cheese. Bake at 400°F (200°C) for about 10 minutes, until the cheese is melted and lightly browned.

Serve immediately.