Preheat your oven to 400°F.
Mix butter with minced garlic thoroughly.
Spread garlic butter on bread halves evenly.
Bake bread for 8-10 minutes until golden.
Heat skillet over medium-high heat.
Cook ground beef until browned completely.
Add diced onion and bell pepper.
Cook vegetables for 5 minutes until soft.
Stir in tomato paste and cook briefly.
Add marinara sauce and Italian seasoning.
Simmer mixture for 10 minutes, stirring occasionally.
Season with salt and pepper to taste.
Remove garlic bread from oven when crispy.
Spoon meat mixture onto bread bottom halves.
Sprinkle mozzarella cheese over meat mixture generously.
Top with fresh parsley for color.
Cover with bread top halves and serve.