In a small bowl, mix together the melted butter, minced garlic, chopped parsley, oregano, salt, black pepper, and red pepper flakes (if using).
Take the Italian bread loaf and make cuts approximately 1 inch apart across the top and down the length of the loaf, being careful not to cut all the way through the bottom.
Gently pry open the cuts of the bread and drizzle or brush the garlic butter mixture generously into each crevice.
Stuff the shredded mozzarella and cheddar cheese mixture into the slits of the bread, making sure it's evenly distributed.
Wrap the entire loaf in aluminum foil and place it on a baking sheet.
Bake in the preheated oven for 15 minutes. After 15 minutes, remove the foil and bake for an additional 10 minutes, until the cheese is melted and bubbly and the bread is golden brown.
Remove from the oven and let it cool slightly before pulling apart and serving.