Add the oil to a large pan with the heat OFF. Add the peeled and lightly crushed garlic, then turn the heat to medium. Gently fry the garlic to infuse the oil, stirring as you go, until the garlic is light golden.
Pour in the passata, then swill out the jar with 1/4 cup of water and add that in too. Add 1/2 of the bunch of basil and the parmesan rind alongside a good pinch of salt. Give everything a stir and bring to a simmer.
Gently simmer for 25 minutes, stirring occasionally, until the sauce thickens. Use tongs or a fork to pluck the basil, parmesan rind and garlic out of the sauce and discard, then check for seasoning and adjust (generously if needed) to bring the best out of the simple sauce.
During this time, preheat the oven to 430F/220C.
A couple of minutes before the sauce is done, add the gnocchi to salted boiling water and cook for 1 - 2 minutes (you'll notice them starting to float to the surface). Keep in mind it'll continue cooking in the oven.
Drain the gnocchi and stir through the sauce, then pour everything into a baking dish. Cover with mozzarella, then sprinkle over the parmesan. Bake for 18-20 minutes, or until deep golden and bubbly.
Serve with plenty of fresh basil (small leaves or torn larger ones). I also like a few pinches of black pepper. Enjoy!