Meatballs

Preparation

1. If using, sprinkle 1 tsp gelatin over 65 ml chicken stock in a heatproof measuring cup and let stand for 5 minutes. Microwave, stirring once or twice, until dissolved, about 2 minutes. Pour into a wide heatproof bowl and refrigerate until fully set, about 30 minutes.
2. In the bowl of a stand mixer (or any large bowl), toss 45 g bread with 45 ml buttermilk. Let stand, tossing occasionally, until completely moist, about 10 minutes — squeeze a few cubes to check; if any dry spots remain, add more buttermilk 1 tablespoon at a time.
3. Mince the 0.5 onion and 15 g parsley; finely mince the 45 g pancetta and 4 cloves garlic. Add to the bread along with 30 g Parmigiano-Reggiano, 2 egg yolks, 0.5 tsp oregano, 0.5 tsp ground fennel, 6.5 g salt, and pepper. If using, finely mince the gelled stock and add it too.
4. Beat the bread mixture until thoroughly blended — in the stand mixer with the paddle, starting at low speed and gradually increasing to medium-high and scraping down the sides as needed, or vigorously by hand for smaller batches. Add a third each of the 250 g beef and 250 g pork and beat until blended.
5. Add the remaining beef and pork. With a clean hand, gently mix, teasing the meat apart with your fingers, just until no unmixed pockets remain — don't overmix.
6. Preheat the broiler with a rack in the upper position and line a rimmed baking sheet with foil. Form the mixture into balls of 80–100 g each, arrange on the sheet, and broil until browned on top, about 7 minutes depending on your broiler.
7. Heat 650 g tomato sauce in a medium pot until simmering, add the meatballs, and simmer until just cooked through (63°C in the center), about 10 minutes.
8. Serve with sauce spooned over and more cheese grated on top.