In a large skillet, on medium-high heat, place the olive oil. Once it is hot, add the onions, garlic, Italian seasoning, dried basil, salt, black, and red pepper. Cook for 2 minutes.
Once the onions and spices have started to soften, add the ground beef and cook for an additional 5 to 6 minutes or until the meat is no longer pink. Drain any excess grease from the cooked beef.
Add the crushed tomatoes to the cooked beef, turn the heat to medium-low, and simmer the sauce for 15 to 20 minutes.
Preheat oven to 375°F. Place a piece of aluminum foil onto a large baking sheet and set it aside.
While the sauce is simmering, remove your garlic bread from the package and allow it to thaw completely. Once thawed, cut your bread in half so that you have 4 equal-sized portions. Place the pieces of garlic bread onto the prepared baking sheet garlic/butter side up.
Carefully cut a slit with a sharp knife, following the shape of the bread, about ¼ inch from the sides of the bread. Make sure you do not go all the way through the bread. You want to create a border to hold the spaghetti and sauce in the bread boat.
With the bottom of a large soup spoon, press down the center part of the garlic bread, making sure to leave ¼ inch border you created with your knife cut. You should have created a garlic bread boat.
In a large bowl, add your cooked and drained thin spaghetti noodles with 4 cups of your sauce. Combine them so that all of your spaghetti noodles are coated with sauce.
Divide your sauce-coated noodles into 4 equal amounts and fill your garlic bread boats with the spaghetti. Make sure to keep your spaghetti neatly piled onto the garlic bread.
Top each of your spaghetti-filled garlic boats with a ¼ of the shredded mozzarella cheese.
Bake for 25 minutes, or until the cheese is melted and lightly golden. If you want your cheese a little more golden, then you can turn on your broiler for 2 to 3 minutes or until desired doneness.