Preheat your oven to 200°C (390°F). Lightly grease a medium baking dish with the softened unsalted butter and set it aside.

Heat the extra-virgin olive oil in a large skillet over medium heat. Add the finely sliced garlic and cook gently for about 1 minute, just until fragrant and lightly golden, stirring so it does not burn.

Pour the passata into the skillet with the garlic. Season with the fine sea salt, freshly ground black pepper, and dried oregano. Stir well to combine and bring the sauce to a gentle simmer.

Let the tomato sauce simmer on low heat for 12–15 minutes, stirring occasionally, until it slightly thickens and the flavors come together. Turn off the heat and stir in the torn fresh basil leaves.

While the sauce is simmering, bring a large pot of water to a boil. Add the tablespoon of fine salt to the boiling water.

Add the potato gnocchi to the boiling salted water. Cook them until they float to the surface, usually 2–3 minutes, then wait about 30 seconds more.

Using a slotted spoon, lift the cooked gnocchi directly from the pot into the skillet with the tomato sauce. Gently toss to coat the gnocchi evenly in the sauce, being careful not to break them.

Transfer about half of the sauced gnocchi to the prepared baking dish. Scatter half of the mozzarella cubes and half of the grated Parmesan cheese evenly over the top.

Add the remaining gnocchi and sauce to the dish, then top with the rest of the mozzarella cubes and grated Parmesan cheese, spreading them out as evenly as possible.

Place the baking dish in the preheated oven and bake for 12–15 minutes, until the cheese is melted and bubbling and the edges are lightly golden.

Remove the Gnocchi alla Sorrentina from the oven and let it rest for 5 minutes before serving so the sauce settles slightly and the cheese firms up just a bit.