Preheat oven to 200°C (top and bottom heat).

Wash the eggplant, halve it lengthwise twice, and slice it as thinly as possible. Add a teaspoon of oil to a pan and sauté the eggplant slices with a generous pinch of salt over medium-high heat for about 5 minutes. Meanwhile, peel and finely dice the shallot and garlic, and wash and halve the tomatoes.

Remove the eggplant from the pan and set aside. Sauté the diced onion and garlic in the remaining oil over medium heat until translucent. Then add the tomatoes, tomato paste, and sugar, and cook for a few minutes, stirring occasionally.

Reduce the heat, add the passata and ricotta, and stir well. Return the eggplant to the pan, stir well, and simmer with the sauce for one to two minutes. Season to taste with oregano, salt, and pepper.

Stir the gnocchi into the sauce and transfer everything to a casserole dish. Cut the mozzarella into thin strips and distribute them over the casserole. Bake the gnocchi casserole in the oven for 15 minutes, or until the mozzarella is melted. Garnish with fresh basil before serving, if desired.