Sauce:
Sauté – In a small saucepan over medium-high heat, warm the olive oil. Add the garlic, finely chopped onion, bay leaf, thyme, and oregano. Cook for 3–4 minutes, stirring occasionally, until the onion becomes soft and translucent. Stir in the tomato paste and cook for another minute to deepen the flavor.
Reduce wine – Pour in the wine, raise the heat to high, and let it simmer briskly for about 2 minutes, or until it has mostly evaporated.
Simmer – Add the tomato passata, vegetable stock, sugar, salt, and pepper. Stir everything together, reduce heat to low, and simmer uncovered for 20 minutes. Keep warm and use the sauce while it’s hot.
Filling:
Squeeze spinach – Take small handfuls of the thawed spinach and squeeze tightly to remove as much moisture as possible.
Mix filling – In a large bowl, combine the well-drained spinach with the rest of the filling ingredients: ricotta, Parmesan, shredded cheese, egg, minced garlic, nutmeg (if using), salt, and pepper. Stir until fully mixed and creamy.
Assemble & Bake:
Preheat your oven to 200°C (400°F), or 180°C (350°F) if using a fan-forced oven.
Stuff – Using uncooked jumbo pasta shells, generously fill each one with the spinach and ricotta mixture. Don’t be shy—fill them all the way.
Assemble – Pour the hot tomato sauce into a 23 x 33 cm (9 x 13 inch) baking dish. Gently nestle the filled shells into the sauce. Most of the shells should be covered by the sauce, though it’s okay if a few peek above the surface.
Bake – Cover the dish with a baking tray or foil and place in the oven. Bake for 70 minutes.
Cheese it! – After baking, check that the shells are al dente and tender. If they’re not quite done, return to the oven, still covered, for a bit longer. Once ready, uncover and sprinkle mozzarella and Parmesan evenly over the top. Bake for another 15 minutes until the cheese is melted, bubbly, and slightly golden.
Serve hot, garnished with fresh basil and extra Parmesan if desired!