Preheat oven to 375F. In a large bowl add meat, panko crumbs, egg, salt, pepper, onion,garlic, parmesan cheese. Combine well.
Divide meat and on the bottom flatten out 1/2 of hamburger. On top add spinach, then cheese. Place the other flatten pound of meat and place on top, securing the sides to keep the cheese from coming out.
Place uncooked bacon length wise and cover the top. Sprinkle coarse pepper on top. Bake 1 hr.