The Best Italian-American Meatballs

Ingredients

• packet unflavored gelatin
• homemade chicken stock or low-sodium broth
• ounces crustless fresh white bread, cut into 1/2-inch cubes
• buttermilk, plus more as needed
• medium yellow onion, minced
• ounces fatty pancetta, finely minced
• ounces Parmigiano-Reggiano, grated, plus more for serving
• medium cloves garlic , finely minced
• loosely packed fresh parsley leaves , minced
• large egg yolks
• teaspoon dried oregano
• teaspoon ground fennel seed
• tablespoon Diamond crystal kosher salt ; for table salt use half as much by volu
• Freshly ground black pepper
• pound ground beef
• pound ground pork
• tomato sauce, such as Quick and Easy Italian American Red Sauce, The Best Slow C