Preheat oven to 350°F and line a sheet pan with parchment paper.
In a large skillet over medium heat, brown ground beef until no longer pink.
Add spaghetti sauce, salt, and pepper; reduce heat to low and simmer for 10 minutes.
Add cooked noodles and toss to fully coat with sauce.
In a bowl, mix melted butter, garlic, kosher salt, and parsley to make garlic butter.
Cut centers out of the tops of the rolls, leaving the bottoms intact to create bread bowls.
Brush garlic butter inside and outside of each roll using 2–3 tablespoons per roll.
Place 1 tablespoon mozzarella into the bottom of each bread bowl.
Fill with about ½ cup spaghetti mixture.
Top with another tablespoon of mozzarella.
Bake for 7–10 minutes or until bread is golden and cheese is melted.
Garnish with fresh parsley and serve hot.