Preheat your oven to 375°F (190°C). Gather all ingredients and equipment.

In a large mixing bowl, combine ground beef, Italian sausage, breadcrumbs, eggs, garlic powder, onion powder, Italian seasoning, salt, and pepper. Mix gently until combined.

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

On parchment paper, flatten the meat mixture into a rectangle about 1/2 inch thick.

Spread the cheese filling evenly across the center of the meat mixture. Roll tightly and seal the edges.

Place the rolled meatloaf seam-side down on a baking sheet. Bake for 45-50 minutes until internal temperature reaches 160°F (71°C).

During the last 10 minutes of baking, add marinara sauce on top of the meatloaf.

Let the meatloaf rest for 10 minutes before slicing. Serve and enjoy!