Serves 4 to 6 (makes about 10 handball-sized meatballs)
Why this recipe works:
A panade made from buttermilk-soaked fresh bread adds tons of moisture and flavor.
Minced pancetta and gelled stock (optional) guarantee extremely juicy meatballs.
Plenty of onion, garlic, and other flavors deliver a rich, satisfying meatball.
Note: This recipe makes about 10 handball-sized meatballs; you can make them smaller or larger, as you prefer, but cooking times will change. The chicken stock and gelatin are optional and help make meatballs that are insanely juicy and tender, but these meatballs will still be incredibly moist even without them. We did not use either . . .
When measuring salt it is important to use the type of salt specified in the recipe. If measured by weight, the saltiness will be consistent regardless of the type of salt used.
The pancetta in this recipe adds juiciness and moisture, so the fattier the better.
1 packet unflavored gelatin (optional, see note above)
1/2 cup homemade chicken stock or low-sodium broth (optional, see note above)
4 ounces fresh white bread, crusts removed and bread cut into 1/2-inch cubes (about 2 unpacked cups)
1/3 cup buttermilk, plus more as needed
1 medium onion, minced
8 cloves garlic, finely minced
2 ounces grated Parmigiano-Reggiano, grated, plus more for serving.
1/2 cup loosely packed fresh parsley leaves, minced
4 teaspoons kosher salt (18 grams; see note above)
Freshly ground black pepper
3 ounces fatty pancetta, finely minced (see note above)
4 large egg yolks
1 teaspoon dried oregano
1 teaspoon ground fennel seed
1 pound ground beef (at least 25% fat)
1 pound ground pork (at least 25% fat)
In a heatproof measuring cup, sprinkle gelatin all over surface of stock and let stand for 5 minutes (if not using stock and gelatin, proceed to Step 2). Microwave stock, stirring once or twice, until gelatin completely dissolves, about 2 minutes. Pour stock into a wide heatproof bowl and refrigerate until fully set, about 30 minutes.
In the bowl of a stand mixer, combine bread with buttermilk, tossing to coat. Let stand, tossing occasionally, until bread is completely moist, about 10 minutes. Squeeze bread between your fingers or mash with a spoon to make sure there are no dry spots; if there are dry spots that refuse to moisten, add more buttermilk 1 tablespoon at a time until bread is moist throughout.
Add onion, garlic, Parmigiano-Reggiano, parsley, salt, pepper, pancetta, egg yolks, oregano, and fennel to bread/buttermilk mixture. Finely mince gelled stock, if using, and add.
Set mixer bowl in stand mixer and attach paddle. Starting at low speed and gradually increasing to medium-high speed, beat bread mixture until thoroughly blended, stopping to scrape down sides as necessary. Add 1/3 each of the beef and pork and beat at medium-high speed until thoroughly blended with bread mixture.
Remove bowl from stand mixer and add remaining beef and pork. Using a clean hand, gently mix meatball mixture, teasing apart ground meat with your fingers, just until ground beef and pork and thoroughly distributed throughout; avoid mixing any more than is necessary for even distribution.
Preheat broiler and set oven rack in upper position. Line a rimmed baking sheet with aluminum foil. Form meatball mixture into handball-sized balls and arrange on prepared baking sheet; you should be able to make about 10. Broil meatballs until browned on top, about 7 minutes (browning times can vary dramatically, depending on oven broiler strength).
Heat tomato (Sunday) sauce in a medium pot until simmering and add meatballs. Simmer until meatballs are just cooked through and register about 145°F on an instant-read thermometer, about 10 minutes.
Serve meatballs, spooning sauce all over and grating more cheese on top.