While the oven is heating, take a small mixing bowl and combine the melted butter, minced garlic, chopped parsley, oregano, salt, black pepper, and optional red pepper flakes. Mix well to ensure even distribution of flavors.
With the Italian bread loaf, make vertical cuts approximately 1 inch apart along the top, extending down the length of the loaf but taking care not to slice all the way through the base. This will create pockets in the bread for stuffing.
Gently open up the cuts you've made in the bread. Using a spoon or a brush, generously drizzle or paint the garlic butter mixture into each crevice, making sure each slit is filled with flavor.
Next, take the shredded mozzarella and cheddar cheese, and stuff it into the slits of the bread. Aim for an even distribution to ensure each piece is cheesy and loaded.
Carefully wrap the entire filled loaf in aluminum foil, sealing it tightly to maintain moisture. Place the wrapped loaf on a baking sheet to catch any drips during baking.
Bake the bread in the preheated oven for 15 minutes. After this time, carefully unwrap the foil and continue baking for an additional 10 minutes. This step will allow the cheese to melt and become bubbly while giving the bread a lovely golden crust.
Once baked to perfection, remove the garlic bread from the oven and allow it to cool for a few minutes. This slight cooling will make it easier to pull apart and ensure you don’t burn your fingers.