Preheat the oven to 375°F (190°C) and line a baking sheet with parchment paper.

Slice the tops off the bread bowls and hollow out the centers, leaving a 1/2-inch thick shell.

In a small bowl, combine the softened butter, minced garlic, parsley, and salt.

Generously brush the interior and edges of the bread bowls with the garlic butter mixture.

Place the bread bowls on the baking sheet and toast for 8 minutes until edges are golden.

While bread toasts, cook spaghetti in boiling salted water until al dente. Drain well.

Heat marinara sauce in a large skillet, add the cooked spaghetti, and toss to coat evenly.

Divide the spaghetti mixture among the toasted bread bowls.

Top each bowl with shredded mozzarella and grated Parmesan cheese.

Bake for 10 to 12 minutes until the cheese is melted and bubbling.