Melt the butter, with the garlic and salt, added, in a heatproof bowl in the microwave. Then, stir in the parsley, rosemary, and basil.
Cut the bread on the bias (diagonally) into 1-inch slices. Then, do so again at a criss-cross angle, creating a pattern of 1-inch diamonds. But do not cut all the way through (as if slicing a loaf for garlic bread).
Using your fingers or a utensil, pry open each crack and drizzle in a small amount of the butter and herb mix. Then, stuff in pinches of mozzarella cheese throughout the loaf. Repeat with Parmesan, and sprinkle some over the top as well. You don't need to be super neat—no penalty for having some of the butter and cheeses drizzled over the crust!
Wrap with foil, and bake for 20 minutes. To make your Stuffed Cheesy Garlic Bread extra crusty, unwrap it for the last 5 minutes of baking. Serve, and enjoy!