Preheat your oven to 375°F (190°C) and prepare your baking sheet or loaf pan by greasing it lightly.
In a large mixing bowl, combine ground beef, Italian sausage, breadcrumbs, Parmesan cheese, onions, and garlic.
Add oregano, basil, salt, and pepper to the mixture, followed by beaten eggs and milk. Mix thoroughly until evenly combined.
Lay out the meat mixture on a flat surface, shaping it into a rectangle. Lay the mozzarella cheese, sun-dried tomatoes, and fresh basil in the center.
Gently roll the meat around the stuffing, sealing the edges completely to form a loaf shape.
Transfer the meatloaf onto your prepared baking sheet or loaf pan, and place it in the oven. Bake for 45 minutes to 1 hour, until the internal temperature reaches 160°F (71°C).
Let the meatloaf rest for about 10 minutes before slicing. This allows the juices to redistribute, ensuring a moist result.
Notes
For best results, slice the meatloaf and wrap the leftovers in foil; store in the refrigerator. Freeze in individual portions for up to 3 months.