Serves 6 as a starter
• 1 lb whole-milk ricotta cheese
• 1 large egg plus 1 large egg yolk, lightly beaten together
• About ½ cup finely grated Parmigiano-Reggiano, plus more for garnish
• Pinch of freshly grated nutmeg
• Kosher salt
• Black pepper in a mill
• 1 lb basic pasta dough
• 8 Tbsp (1 stick) unsalted butter
• ¼ cup (loosely packed) thinly sliced herbs such as basil, mint, tarragon, and/or chervil
• 2 oz thinly sliced prosciutto, torn into bite-sized pieces
Make the tortelli
Put the ricotta, whole egg, egg yolk, Parmigiano-Reggiano, and nutmeg in a medium-sized bowl. Season with salt and pepper and fold together with a rubber spatula until just incorporated. Spoon the ricotta mixture into a piping bag fit with a No. 3 plain tip and refrigerate to chill for at least 1 hour, but not more than 8 hours.
Roll pasta dough through a pasta machine set to the thinnest setting. Working on a floured surface, use a wheel cutter or sharp chef’s knife to cut the pasta sheets into 3” by 3” squares. Pipe about 1½ tablespoons of filling into the centers of half of the squares. Use a pastry brush or an immaculately clean finger to brush the edges with water, and place another square on top, using your fingers to push out any air. Tightly seal the edges and trim the edges with the pasta roller. As they are made, gather the tortelli on a flour-dusted baking tray.
When ready to cook and serve the tortelli, fill a medium-sized pot about two-thirds full with water, salt it liberally, and bring to a boil over high heat. While the water is coming to a boil, heat a wide, heavy-bottomed pot over medium-high heat. Add the butter and let it melt, tipping and tilting the pan to coat it.
When water comes to a boil, lower the heat slightly so the water is boiling gently, then gingerly deposit the tortelli in the water a few at a time. Stir carefully once to keep them from sticking, but taking care to not break them. The tortelli are done when they float to the surface, 2 to 3 minutes for fresh or 4 to 5 minutes for frozen. Remove them with a slotted spoon and gather in a bowl or very gently drain in a colander.
Add the herbs to the melted butter and cook for a minute, then add the drained tortelli to the pan and toss briefly to coat the pasta with the butter. Toss in the prosciutto, divide among individual plates, sprinkle each serving with Parmigiano-Reggiano, and serve immediately.