To make the pasta dough, put the shredded greens, eggs, salt, and olive oil in a blender or food processor and puree until smooth. Scrape the green puree into a mixing bowl and add the flour. Knead into a soft dough. If the dough seems too sticky, sprinkle with
For the filling, heat the olive oil in a large deep saucepan over a medium-high flame. Add the garlic and let it sizzle, without browning. Add the red pepper flakes, then add the greens. Stir well and let the greens wilt for a minute. Season with salt and pepper and stir again.
Now put the wilted greens in a colander to drain. When the greens are cool enough to handle, squeeze them in your hands to remove any excess liquid. Set them aside.
Put the ricotta in a bowl. Add the lemon zest, season with
For the béchamel sauce, melt the butter in a large heavy-bottomed saucepan over a medium flame. Stir in the flour and cook, stirring, for a minute, without letting the mixture brown. Whisk in the milk a half cup at a time, letting the sauce thicken after each addition. When all the milk has been added, add the bay leaf and thyme and season with salt and pepper.
Turn the flame to low and let the sauce cook gently for 10 minutes. Thin if necessary with a little more milk. Grate in some nutmeg. Check the seasoning and adjust. Strain the sauce into a double boiler and keep warm.
Butter a large baking dish, approximately 8 by 12 inches. Have a large pot of salted boiling water on the stove and a large bowl of cold water nearby.
Divide the dough into 3 or 4 pieces. Roll each piece into a thin sheet with a pasta machine at the next-to-thinnest setting, placing the pieces on a floured counter as you work. Cut the sheets into 8-inch lengths. Leave the pasta sheets uncovered on the floured counter.
To assemble the lasagne, boil 2 sheets of pasta at a time so they cook evenly and don’t stick together. Cook the sheets as you go, for 1 minute or less, leaving them quite al dente. Plunge them immediately in the cold water to stop the cooking, then blot on a kitchen towel.
For the first layer, lay the 2 pasta sheets side by side in the bottom of the gratin dish. Arrange a quarter of the cooked greens over the pasta. Dot the greens with one-quarter of the ricotta. Spoon ½ cup béchamel sauce over the ricotta, and sprinkle with a handful (about 2 tablespoons) of Parmigiano. Repeat the process to make 3 more layers. Finish with 2 or 3 sheets of pasta on top, coat with the remaining béchamel, and sprinkle with the rest of the Parmigiano.
Refrigerate the assembled lasagne for up to several hours, or overnight to marry the flavors. Bring to room temperature before baking.