For the sunchoke and ricotta filling: Scrub and then carefully peel the sunchokes. Slice thinly, and then submerge immediately in ice water.
Heat some olive oil in a heavy-bottomed saucepan over medium heat. Sweat the garlic and onions until softened (do not allow them to color). Drain the sunchokes and pat dry, then add to the pan and cook until soft, adding small amounts of water to keep the vegetables from coloring. Season with salt and pepper, and discard any excess liquid. Carefully ladle small quantities at a time into a blender and puree until smooth and velvety. Mix the sunchoke puree with the Fresh Ricotta, Parmigiano-Reggiano, mixed herbs and lemon zest. Taste and adjust the seasoning.
For assembling the cappelletti: Flatten the dough with a rolling pin on a floured surface, forming a rectangular shape with the wider side facing you. Fold the dough as you would a letter: lay the right third of the dough over the center, and then fold the left third over on top. Roll the folded dough through a pasta machine at progressively narrower settings until you've created a 5-inch-wide sheet. Fold the dough into thirds again. Pass the folded dough back through the machine on the widest setting, and then continue rolling through until it is thin enough to be slightly translucent, but still thick enough to hold its shape.
Lay the resulting pasta sheet on a lightly-floured surface with a long side facing you. Cut out 2-inch-diameter circles of dough using a round cookie cutter. Place a teaspoon of sunchoke and ricotta filling into the middle of each circle, and then fold over to make half-moons, dampening the edges with water to make sure they adhere. With the flat side facing away from you, connect the half-moon corners to each other, making sure to have a flat, cohesive connection. The resulting pasta will be in a sailor-hat shape.
Transfer immediately to a semolina-dusted baking sheet to prevent sticking, keeping the cappelletti separate so they don't stick together.
For assembling the dish: Cook the cappelletti to al dente in salted boiling water, about 4 minutes, and then carefully drain, reserving 1 cup pasta cooking water. Melt the butter along with 4 tablespoons pasta water over medium-high heat in a deep saute pan, stirring well. Add the cappelletti, raw nettles and lemon juice and cook until the sauce thickens to the point where it coats the back of a spoon, adding more pasta cooking water if needed.
Check and adjust the seasoning. Garnish the cappelletti with the fried nettles and Parmigiano-Reggiano and serve immediately.
Line a colander or sieve with a wide surface area with a large piece of cheesecloth that has been folded numerous times to create 3 or 4 layers. Place the lined colander over a large bowl or the sink. Slowly heat the milk, cream and salt to 180 degrees F over moderate heat in a 4-quart heavy pot, stirring occasionally to prevent scorching. Add the lemon juice and reduce the heat to low, stirring occasionally, until the mixture curdles, about 2 minutes. Pour the mixture into the colander and let drain up to 1 hour. Discard the liquid, cover the ricotta and let chill. It will keep in the refrigerator up to 2 days.
Combine the flour, olive oil, salt and egg in a mixer with a dough hook attachment, and mix until the dough comes together. If too crumbly, add a small amount of water until the dough forms into a ball. (Be careful not to add too much water, or the dough will become sticky and unworkable.)
Turn the dough out onto a floured surface and knead by hand until smooth and elastic, 10 to 20 minutes. Wrap in plastic and let rest at least 20 minutes and up to 24 hours.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.