To make the pasta, place the flour in a bowl, make a well in the centre and crack the eggs in.
Use a fork to break up the eggs and mix them with the flour.
When the dough starts to form clumps, turn out onto a floured surface and knead until it comes together. Continue kneading for two minutes to form a smooth dough ball.
Divide the dough in half, and wrap each piece in clingfilm. Chill for 60 minutes while you prepare the filling.
Wash the spinach, removing any tough stalks. Wilt in a hot pan for a few minutes, taking care not to overcook.
Transfer the wilted spinach to a tea towel and squeeze out any extra moisture. Finely chop the spinach, or process in a mini food processor.
Combine the spinach, ricotta cheese, Parmesan, egg, olive oil and nutmeg together in a bowl. Season well to taste and chill until the dough is ready.
Roll out the pasta dough on a floured surface to a thickness of 1 mm with a rolling pin or a pasta machine.
Drop spoonfuls of the spinach and ricotta filling along one sheet of the pasta dough, leaving an inch and a half between each spoonful.
Using a finger dipped in water, wet the edges of the ravioli, around the filling. Carefully arrange another pasta sheet over the top and press into place, starting from the middle. Use your palms to cup around the filling and press any air bubbles out.
Use a sharp knife or fluted pasta cutter to cut out each indivdual ravioli. Place on a floured baking tray and cover with a damp tea towel until the rest are made.
To prepare the tomato sauce, if using, heat four tbsp olive oil in a small saucepan and saute the garlic for a minute or so, until it imparts its fragrance.
Add the passata and cook for a few more minutes, until thick and bubbling. Add the fresh basil, season well and remove from the heat. Stir in another tablespoon of good quality olive oil.
Bring a large pot of salted water to a simmer and drop the ravioli in. Cook for four minutes. They will float when ready. Remove with a slotted spoon, drain and arrange on a serving plate.
Serve simply with a drizzle of good quality olive oil and some Parmesan, or with the tomato sauce and Parmesan cheese.