Step 1: Preheat the Oven - Preheat your oven to 375°F (190°C) for golden, bubbly bread.
Step 2: Prepare the Garlic Butter - Melt the butter in a saucepan over medium heat, add minced garlic, and sauté for 1-2 minutes. Stir in parsley, salt, and pepper.
Step 3: Cut the Bread - Make deep crisscross cuts in the sourdough loaf without slicing through the bottom.
Step 4: Stuff the Bread - Drizzle garlic butter mixture between the cuts, then sprinkle in Parmesan and mozzarella cheese.
Step 5: Wrap and Bake - Wrap the loaf in aluminum foil on a baking sheet and bake for 15 minutes.
Step 6: Unwrap and Broil - Unwrap the foil and broil for 5-7 minutes until cheese is bubbling and golden.
Step 7: Serve and Enjoy - Cool slightly, then serve warm, pulling apart the cheesy sections.