1 8-ounce bag of frozen, chopped spinach, thawed and drained
½ cup finely grated Parmigiano-Reggiano cheese, plus additional for garnish
Kosher salt, to taste
Freshly grated nutmeg, to taste
Freshly ground black pepper, to taste
Brown Butter Sauce
½ lb unsalted butter
1 sprig rosemary
1 sprig sage
1 sprig thyme
Egg Yolk Raviolo
Mix together the flour and dried parsley on a clean surface and make a well in the center. Add the egg yolks, eggs, and salt to the well and slowly beat with a fork, gradually incorporating flour from around the edges of the well.
When the dough starts to come together, switch to your hands and knead until the dough is smooth and supple, 20–30 minutes.
Alternatively, combine the ingredients in a stand mixer fitted with a dough hook and beat on low speed until smooth and pliable, about 15 minutes.
Wrap the dough tightly in plastic wrap and let rest at room temperature for 2 hours.
Cut the dough in quarters using a bench scraper or knife.
Set 1 section aside to work with, and return the rest to the plastic wrap or cover with a kitchen towel.
Sheet the dough with a pasta roller attachment to a stand mixer
Shape the portion into a rectangle, and lightly dust with flour on each side.
Start the mixer at low or medium speed, and set the roller to the widest setting.
Take the resulting pasta and fold it like a book (lay it lengthwise on your board, fold each short edge into the middle).
Repeat the process 2-4 times.
Move up to the second widest setting and run the dough through twice (no folding this time). Run the dough through each subsequent setting until the second thinnest setting. Lightly flour the dough as needed.
Cut the dough into 4-inch squares.
Pipe 2 tablespoons whipped ricotta filling in a circle, about 2-inches in diameter in the center of each square of dough.
This will create a border of ricotta that will contain and support the egg yolk.
Place an egg yolk in the circle and pipe 1 tablespoon more filling on the yolk to enclose.
Mist dough lightly with water and place another piece of dough on top to seal.
Press firmly and use a fluted cookie cutter or Rotolo to cut into the desired shape.
Repeat with the remaining squares of dough.
Bring a large pot of salted water to a simmer (not boil).
Place the fresh raviolo into the water and return the water to a simmer.
Continue to cook for 3-4 minutes, being careful not to overcook the yolk.
Remove from the water and transfer to a serving plate.
Spoon the brown butter mixture over the raviolo and top with grated Parmesan cheese.
Add the ricotta to a strainer or wrap in cheesecloth and hang over a medium bowl.
Refrigerate overnight to drain excess moisture.
This step is optional but will help you achieve an extra creamy filling.
In a food processor, combine the ricotta, spinach, Parmigiano-Reggiano, nutmeg, to taste and salt to taste, and blend until smooth and rich, scraping down the sides with a rubber spatula as needed.
Season with salt and pepper to taste.
Transfer whipped ricotta to a piping bag.
Brown Butter Sauce
In a small saucepan over medium heat, melt butter, and begin whisking until brown, 4-6 minutes.
Immediately add herbs to the pan, turn off the heat and allow to infuse, 2 minutes.