Preheat and Prep: Preheat your oven to 180°C (160°C fan). Lightly grease a 9x13 inch (23x33 cm) baking dish. Pour about a third of the tomato passata into the bottom of the dish and spread it evenly. Stir the dried oregano into the remaining passata.

Cook the Lasagna Sheets: Bring a large pot of salted water to a boil. Cook the lasagna sheets according to the package directions, usually for about 8-10 minutes, until they are pliable but still have a slight bite (al dente). What works best for me is to carefully remove them with tongs and lay them flat on a clean, lightly oiled baking sheet to prevent them from sticking together.

Prepare the Spinach: While the pasta cooks, place the fresh spinach in a large colander. Pour boiling water over it to wilt it completely. Once it's cool enough to handle, squeeze out all the excess water. This step is crucial! Finely chop the spinach.

Mix the Filling: In a large bowl, combine the shredded chicken, chopped spinach, ricotta cheese, grated Parmesan, beaten egg, minced garlic, and ground nutmeg. Season generously with salt and black pepper. Mix everything together until it's thoroughly combined.

Assemble the Rolls: Lay one cooked lasagna sheet flat. Spread about 2-3 tablespoons of the chicken and spinach filling evenly over the surface, leaving a small border at the edges. Carefully roll it up from one of the shorter ends to create a neat cylinder.

Arrange in the Dish: Place the finished roll seam-side down in the prepared baking dish. Repeat with the remaining lasagna sheets and filling, arranging them snugly in a single layer.

Add Sauce and Cheese: Pour the remaining oregano-seasoned passata over the top of the rolls, ensuring they are well-covered. Sprinkle the grated mozzarella evenly over the sauce.

Bake to Perfection: Place the dish in the preheated oven and bake for 25-30 minutes, or until the sauce is bubbling and the cheese on top is melted, golden brown, and slightly crispy at the edges.

Rest and Serve: Let the lasagna rolls rest for about 5-10 minutes before serving. This allows them to set up a bit, making them easier to serve. Garnish with fresh basil leaves and an extra sprinkle of Parmesan cheese.