Whenever I make pasta and meatballs, I think of the classic scene in “Lady and the Tramp” when the main characters fall in love over a bowl of shared pasta. The first key to this recipe is making sure all of your ingredients are at room temperature; it ensures that your food will cook evenly and more quickly. Also, mixing the meat by hand is the most effective, but if you’re squeamish about it, trying wearing gloves. Finally, don’t be afraid to aggressively salt your pasta water, without enough salt, your pasta won’t have enough flavor.
Preheat the oven to 300 degrees F. Fill a large pot with 4 to 6 quarts of water and 3 tablespoons salt and bring to a robust boil over high heat.
Combine the beef, pork and veal in a large bowl and mix well, ideally using your hands.
Put the breadcrumbs, onions, parsley, garlic and egg in a small bowl. Season with salt and pepper and stir until well mixed.
Add the breadcrumb mixture to the meat mixture and combine with your hands—they’re still the best tool for this.
Form the mixture into golf ball-size meatballs by rolling them between your palms, wetting your hands with water as needed to keep the meat mixture from sticking to your skin.
Preheat a large cast-iron skillet or other ovenproof saute pan over medium heat. When the skillet is hot, add just enough olive oil to coat the bottom and add the meatballs without crowding. Cook until a nice crust forms on the bottom of the meatballs, about 5 minutes. Flip with tongs, turn off the heat, add 1/4 cup water and cover the skillet with aluminum foil.
Place the skillet in the oven and bake until the meatballs have reached 165 degrees F and have just a spot of pink in the center, 10 to 12 minutes.
Meanwhile, add the pasta to the salted boiling water. When the water returns to a boil, stir the pasta well so it doesn’t stick. Cook until al dente, 2 to 3 minutes.
Heat the marinara sauce in large pot or skillet over medium-low heat until simmering. Add the cooked meatballs, stir gently and allow to heat together for 2 to 3 minutes.
Drain the pasta and gently toss with the sauce and meatballs until evenly coated. Serve topped with Parmesan cheese.