Heat the olive oil in a medium saucepan, add the garlic and fry on a low heat till fragrant, about 1–2 minutes, then stir in the tomatoes. Simmer on a low heat for 30–45 minutes.
Transfer the sauce to a baking dish approximately 18 x 26cm/7 x 10in.
Place the washed spinach leaves in a medium pan, cover, and cook on medium heat for 2–3 minutes until soft. Drain and finely chop the spinach.
In a bowl, mix the chopped spinach with the remaining ingredients for the filling.
Check the cooking instructions on the packet of lumaconi and cook for 8–10 minutes until al dente. Transfer to a bowl of iced cold water.
Drain the pasta and use a piping bag to stuff each lumaconi with the ricotta mixture.
Place the stuffed lumaconi into the tomato sauce.
Preheat the oven to 180°C fan/400°F/gas mark 6. Place an ovenproof dish half-filled with boiling water on the bottom shelf.
Bake the lumaconi for 20 minutes until the sauce is bubbling and the pasta edges are golden.
Serve with a wedge of Parmesan and a side of sautéed broccoli or a fresh green salad.