Boil the whole potatoes with the skin on in plenty of salted water. Peel them, mash them, and mix with the flour, a tablespoon of Parmesan cheese, and a pinch of salt. Do not overwork the dough. Divide the dough into ropes, cut into small pieces, and shape them using a grater or a fork. Place the gnocchi on a floured tray.

In a skillet with some olive oil, sauté the chopped onion. Add the tomato purée and cook for about 15-20 minutes. Turn off the heat and add 5-6 basil leaves. Meanwhile, cook the gnocchi in plenty of boiling salted water and drain them when they float to the surface. Toss the gnocchi with the sauce and 9 ounces (250 grams) of chopped mozzarella. Arrange the cherry tomatoes in a baking dish, season with a little sugar, a pinch of salt, and a drizzle of olive oil.

Bake for 20 minutes at 300°F (150°C). Place the gnocchi in a baking dish, top with 1 3/4 ounces (50 grams) of chopped mozzarella and the cherry tomatoes, and bake at 350°F (180°C) for 15 minutes. Remove from the oven, garnish with basil, and serve immediately.