Stromboli Sandwiches

This is really yummy! I halved it which was plenty, but I'm putting the original on here:
2 # ground beef
1/4 c finely chopped onion
1 c ketchup
1 c tomato sauce
1/4 c Parmesan cheese
2 t garlic powder, divided
1 t dried oregano
1/2 t fennel seed (?)
1/2 t Italian seasoning
1/2 c butter, softened
2 loaves (1 # each) Italian bread, halved lengthwise (I couldn't find, so I just used French bread)
2 c shredded mozzarella cheese

Cook beef and onion over medium heat until meat is no longer pink; drain. Stir in the ketchup, tomato sauce, Parmesan cheese, 1/2 t garlic powder, oregano, fennel seed and Italian seasoning. Bring to a boil. Reduce heat; simmer, uncovered for 15 minutes or until thickened, stirring occasionally.
Meanwhile, in a small bowl, combine butter and remaining garlic powder; spread over top halves of bread. Sprinkle 1/2 c mozzarella cheese over each bottom bread half. Spoon meat mixture over top; sprinkle with remaining mozzarella cheese. Replace bread tops; wrap each sandwich loaf in foil. Bake at 350 for 25-30 minutes or until cheese is melted.