Step 1: Preheat the Oven
Preheat your oven to 375°F (190°C). Line a baking sheet with aluminum foil for easy cleanup.

Step 2: Prepare the Bread
Using a sharp knife, make deep diagonal cuts in the loaf, creating a crosshatch pattern. Be careful not to cut all the way through; leave the base intact.

Step 3: Make the Garlic Butter
In a small bowl, mix melted butter, minced garlic, Italian seasoning, salt, black pepper, red pepper flakes (if using), and chopped parsley. Stir well to combine.

Step 4: Stuff the Bread
Gently open the cut sections of the bread and drizzle the garlic butter mixture inside, making sure it seeps into every crevice. Stuff shredded mozzarella and Parmesan cheese into the gaps.

Step 5: Bake the Bread
Wrap the loaf in aluminum foil and place it on the baking sheet. Bake for 15 minutes. Then, uncover and bake for another 10-15 minutes until the cheese is melted and bubbly.

Step 6: Serve & Enjoy!
Remove from the oven and let it cool for a minute. Pull apart pieces and enjoy your delicious garlic bread!