Prepare the Garlic Butter: In a medium bowl, combine the softened butter, minced garlic, parsley, Parmesan cheese, garlic powder, salt, and pepper. Mix well until thoroughly combined.

Prepare the Bread Bowls: Preheat oven to 350°F (175°C). Using a serrated knife, carefully cut a circle out of the top of each loaf of bread, leaving a 1-inch border. Remove the bread from the center, creating a bowl shape. Reserve the removed bread for dipping, if desired.

Garlic Butter Application: Generously spread the garlic butter mixture inside each bread bowl, ensuring the bottom and sides are well coated.

Bake the Bowls: Place the prepared bread bowls on a baking sheet and bake for 10-15 minutes, or until the garlic butter is melted and the inside of the bowls are lightly toasted. This step is crucial for creating a moisture barrier.

Prepare the Spaghetti: Cook the spaghetti according to package directions until al dente. Drain well.

Prepare the Spaghetti Sauce: While the pasta is cooking, heat the olive oil in a large saucepan over medium heat. Add the ground beef or Italian sausage and cook, breaking it up with a spoon, until browned. Drain off any excess grease. Add the chopped onion and minced garlic and cook until softened, about 5 minutes. Stir in the crushed tomatoes, tomato sauce, tomato paste, oregano, basil, sugar, salt, and pepper. Bring to a simmer, then reduce heat and cook for at least 30 minutes, or up to 1 hour, stirring occasionally, to allow the flavors to meld and the sauce to thicken.

Combine Spaghetti and Sauce: Add the cooked spaghetti to the saucepan with the spaghetti sauce and toss to coat evenly.

Assemble the Bowls: Carefully fill each baked garlic bread bowl with the spaghetti and sauce mixture.

Garnish and Serve: Garnish with grated Parmesan cheese and serve immediately.