Preheat oven to 400 degrees F. Line a large sheet pan (or two sheet pans if needed) with parchment paper.
In a medium bowl, soak the bread (crust removed and cut into cubes) with the whole milk for about 10 minutes.
Make the meatball mixture: In a large bowl, combine the ground beef and Italian sausage along with the soaked bread, onions, garlic, beaten egg, fresh Italian parsley, fresh basil, dried Italian seasoning, parmesan cheese, Kosher salt (1 teaspoon) and black pepper (½ teaspoon). Using your hands, mix until evenly combined. Do not overmix, as overmixing can make the meatballs tough).
Using a medium cookie scoop or a tablespoon, scoop and form the meatballs into 1.5-2 inches. You should have about 22 to 24 meatballs. Arrange them on the lined sheet pans, making sure they are not too close together for better air circulation.
Bake in the preheated oven for about 20 to 23 minutes. If needed, broil for 2 minutes until golden brown on top.
While the meatballs are cooking, heat the marinara sauce until warm. Also, cook your pasta according to package directions.
Once the meatballs are done, toss them with some of the marinara until lightly coated. Use the remaining sauce to toss with the cooked and drained pasta. Serve the meatballs on top of saucy pasta, and garnish with grated parmesan cheese and fresh parsley. Enjoy!