To make the gnocchi, in a large pot over medium-low heat, combine the water, butter and the 2 teaspoons salt and bring to a simmer. When the butter has completely melted, add the flour all at once and stir with a wooden spoon until the mixture is even and forms a smooth, glossy dough. Continue to cook the dough over medium-low heat until a thin coating starts to form on the bottom of the pot (but is not browning), about 2 minutes. Remove the pot from the heat and cool it inside a sink filled with shallow, cold water (make sure the water doesn’t overflow into the pot). When the pot is cool enough to touch, place it on a clean kitchen towel on the countertop.

Add the mustard, chives, fennel fronds and cilantro and stir with a wooden spoon until evenly blended. Add the cheese and stir until evenly blended. Add the 2 whole eggs, one at a time, and stir into the dough until completely smooth before adding the next egg. Then add the egg yolk and stir until smooth. Check the consistency; a scoop of the dough on a tilted wooden spoon should fall down very, very slowly. If it doesn’t move and seems too stiff or dry, stir in 1 tablespoon of the egg white.

Transfer the dough to a piping bag and let rest at room temperature for 30 minutes. Fill a pot with water, add a good pinch of salt and bring to a simmer. Line a baking sheet with parchment paper. 

Fit a reusable piping bag with a plain tip (if you are using a disposable piping bag, cut a 3/4-inch opening at the tip). Keep the water at a very gentle simmer, then squeeze the dough out of the piping bag while cutting it into the water with a small knife. If the dough is sticking to the knife, dip the knife in the hot water and continue. After the gnocchi have floated to the surface of the water, poach them for 1 to 2 minutes more. Using a slotted spoon, transfer the gnocchi to the prepared baking sheet. Continue to cut the gnocchi into the water and poach in batches.

Evenly scatter the gnocchi on the baking sheet and refrigerate until needed or up to 1 day. Alternatively, flash-freeze them until hard and store in an airtight container in the freezer; thaw for about 2 hours before using.

To make the beef cheeks, in an ovenproof 6-quart wide, heavy pot over medium-high heat, warm 2 tablespoons of the olive oil until hot but not smoking. While the oil is heating, pat the beef cheeks dry and season with salt and pepper. Working in batches if needed to avoid overcrowding, add the beef to the pot and brown on all sides, about 20 minutes per batch. Using tongs, transfer the beef to a bowl. 

Pour off the fat from the pot. Set the pot over medium heat and warm the remaining 2 tablespoons olive oil. Add the cipollini onions and cook until nicely browned on both side. Transfer to a small bowl. Reduce the heat to medium-low and add the chopped onion, carrot and celery. Cook, stirring occasionally, until softened, about 10 minutes.

Preheat the oven to 325°F.

Stir the cocoa powder into the vegetable mixture, then add the wine and scrape up the browned bits. Increase the heat to high and boil until the liquid is reduced by half, about 10 minutes. Add the black garlic.

Return the beef cheeks along with any accumulated juices to the pot. Add the tomatoes with juices, cipollini onions, the 1 1/2 teaspoons salt and 1 teaspoon pepper. Bring to a simmer, then cover, transfer to the oven and braise until very tender, about 3 hours.

To serve, in a large fry pan, melt some butter. Working in batches, panfry the gnocchi and transfer to individual plates. Top with the beef cheeks. Garnish with parsley and Parmesan.