Preheat your oven to 375°F (190°C).

In a large bowl, gently mix together ground beef, Italian sausage, breadcrumbs, eggs, garlic powder, onion powder, Italian seasoning, salt, and pepper until just combined.

In a separate bowl, mix together the mozzarella cheese, Parmesan cheese, and spinach.

On a sheet of parchment paper, flatten the meat mixture into a rectangle, then spread the cheesy filling evenly across the surface.

Carefully roll the meat mixture around the filling, sealing the edges well.

Place the rolled meatloaf seam-side down in a baking dish and bake for 45-50 minutes until it reaches an internal temperature of 160°F (71°C).

During the last 10 minutes of baking, ladle marinara sauce over the meatloaf.

Once baked, let the meatloaf rest for about 10 minutes before slicing.