1. Prepare the Bread:

• Preheat the oven to 375°F (190°C) and line a baking sheet with parchment paper.
• Slice the Italian bread loaf in half lengthwise to create two halves.
• In a small bowl, mix the softened butter and garlic powder. Spread the mixture evenly on the cut sides of the bread.
• Place the garlic buttered bread halves on the prepared baking sheet, cut side up.

2. Make the Spaghetti Filling:

• Heat a large skillet over medium heat. Add the diced onion and minced garlic, sautéing for 3–4 minutes until fragrant.
• Add the ground beef and ground sausage, breaking them up into smaller pieces with a spatula. Cook until browned and fully cooked through.
• Stir in the tomato sauce, tomato paste, Italian seasoning, salt, and black pepper. Let the sauce simmer for 10–15 minutes to develop its flavors.
• Meanwhile, cook the spaghetti in salted boiling water until al dente. Drain and mix the cooked spaghetti into the meat sauce.

3. Assemble the Garlic Bread with Spaghetti:

• Sprinkle half of the Parmesan cheese and half of the Mozzarella cheese over one of the garlic buttered bread halves.
• Spread the spaghetti and meat sauce mixture evenly over the cheese-covered bread half.
• Sprinkle the remaining Parmesan and Mozzarella cheese on top of the spaghetti layer.
• Place the other garlic buttered bread half on top, sandwiching the spaghetti between the two halves.

4. Bake:

• Cover the stuffed garlic bread loosely with aluminum foil to prevent it from drying out.
• Bake in the preheated oven for 15–20 minutes, or until the cheese is melted and bubbling.
• Remove the foil and bake for an additional 5–10 minutes, or until the bread is golden and crispy.

5. Slice and Serve:

• Remove the garlic bread with spaghetti from the oven and let it cool for 5 minutes.
• Carefully slice into portions using a sharp knife.
• Garnish with fresh parsley or basil if desired and serve hot.