For the Filling
Mix the ricotta, parmesan, cooked & squeezed spinach (to remove excess water), garlic, lemon zest, nutmeg and a pinch of salt and pepper until well combined.
To Assemble the Tortellini:
If you are making the egg yolk raviolo, put one third of the spinach and ricotta mix aside.
Spoon a heaped teaspoon of filling inside each pasta circle and fold to create a half moon shape. Wet the edges and press down. Pull the two narrow ends together to form a tortellini shape.
Bring a large saucepan of salted water to the boil. Cook the pasta in the boiling water for 2–3 minutes, or until al dente. Drain well.
To Make the Sauce
Meanwhile, melt a knob of butter in a frying pan, add sage leaves and cook for a minute before adding the lemon juice and a bit of pasta water, simmer until thick and glazy.
Plate your pasta with the sauce poured over it, grated parmesan and cracked black pepper.