In a large mixing bowl, combine the ground beef, breadcrumbs, Parmesan cheese, chopped parsley, egg, minced garlic, Italian seasoning, and a pinch of salt and pepper. Mix gently until all ingredients are evenly incorporated but do not overmix, or the meatballs will be tough.
Using your hands, form the meat mixture into small meatballs, about 1 to 1.5 inches in diameter. Heat a skillet over medium heat with a little olive oil and brown the meatballs on all sides until they develop a nice crust, about 5-7 minutes. They don’t need to be fully cooked through at this stage since they’ll finish baking in the casserole.
While the meatballs are browning, cook your pasta according to package instructions until al dente. Drain well and set aside.
In a large bowl or directly in your prepared baking dish, mix the cooked pasta with the marinara sauce. Gently fold in the browned meatballs so they’re evenly distributed.
Grease your baking dish with olive oil. Pour the pasta, meatballs, and sauce mixture into the dish. Sprinkle the shredded mozzarella cheese evenly over the top. For an extra layer of flavor and crunch, sprinkle the cooked, crumbled turkey bacon on top.
Preheat your oven to 375°F (190°C). Bake the casserole uncovered for 25-30 minutes or until the cheese is melted, bubbly, and golden brown around the edges.
Let the pasta bake cool for 5 minutes before serving. This allows the cheese to set slightly, making it easier to scoop out hearty portions. Pair it with a simple green salad or garlic bread for a complete meal.