Step 1
Strain the ricotta cheese using a cheesecloth-lined strainer. In a 4‑cup saucepan, combine the spinach, water, and a pinch of salt. Cook over medium-high heat until the spinach wilts. Blend the cooked spinach until smooth and allow it to cool. In a large bowl, make a well with the flour. Add the eggs, olive oil, and spinach purée. Mix until combined—adjust with extra flour or water as needed. Knead the dough on a floured surface until smooth and elastic (it should spring back when poked). Wrap in plastic wrap and refrigerate.
Step 2
Grate the Manchego cheese. In a food processor, combine the olive oil, basil, spinach, walnuts, and cheese. Blend until smooth, then season with lemon juice, lemon zest, salt, and pepper. In a bowl, mix the strained ricotta with half of the pesto. Transfer the mixture to a piping bag and reserve the remaining pesto in the refrigerator.
Step 3
Remove the pasta dough from the refrigerator and cut it into manageable sections. Using a pasta roller or rolling pin, roll the dough to about 1/8‑inch thickness, dusting with flour to prevent sticking.
Step 4
Use a 2‑inch ring mold to cut circles from the rolled dough. Pipe about a tablespoon of filling into the center of each circle. Brush the edges with egg wash, fold in half, and pinch the ends together to form tortellini. Place them on a floured tray.
Step 5
Bring a large pot of salted water to a boil. In a separate pan, combine the heavy cream and the remaining pesto over medium-high heat. Stir until the sauce thickens to a nappé consistency, then reduce the heat to low. Cook the tortellini in the boiling water until they float, about 2 minutes. Use a spider or slotted spoon to transfer them into the sauce, tossing gently.
Step 6
Spoon a little sauce onto the center of each plate and neatly arrange five tortellini on top. Finish by shaving Manchego cheese, zesting lemon, and drizzling olive oil over the dish. Garnish with fresh basil and serve immediately.
