01 - Preheat oven to 350°F. Line a baking tray with parchment paper.
02 - Using a sharp bread knife, cut the sourdough loaf in a criss-cross pattern, making deep cuts while leaving the base intact.
03 - Combine softened butter, minced garlic, parsley, chives, basil, salt, and black pepper in a mixing bowl until well blended.
04 - Carefully open the bread cuts and spread the garlic herb butter evenly throughout the loaf.
05 - Insert shredded mozzarella, cheddar, and grated parmesan into the loaf’s cuts, distributing the cheese evenly.
06 - Place prepared loaf onto the baking tray. Cover loosely with aluminum foil and bake for 15 minutes.
07 - Remove foil and bake for another 8 to 10 minutes until the cheese is melted and golden, and bread edges are crisp.
08 - Serve hot and allow guests to pull apart pieces for sharing.