Start by preheating your oven to 400°F (200°C). While the oven is heating, prepare your bread. Place the loaf of Italian bread or baguette on a cutting board. Using a serrated bread knife, slice the loaf lengthwise, being careful not to cut all the way through the bottom crust. You want to create two long halves, like an open book. This exposes a large surface area for the garlic butter and cheese.
In a medium-sized mixing bowl, combine the softened unsalted butter, minced garlic, finely chopped fresh parsley, salt, and freshly ground black pepper. Using a fork or spatula, thoroughly mix all the ingredients together until well combined and the garlic and parsley are evenly distributed throughout the butter. The softened butter should be easy to mix and create a smooth, aromatic garlic butter mixture. If using red pepper flakes, stir them in at this stage as well.
Take the prepared garlic butter and generously spread it evenly over the cut surfaces of both bread halves. Ensure you cover every nook and cranny of the bread, right up to the edges. Don’t be shy with the garlic butter! This is where most of the flavor comes from. The butter will soak into the bread as it bakes, creating a moist and flavorful interior.
Now it’s time for the cheese! Sprinkle the shredded mozzarella cheese evenly over both halves of the garlic butter-covered bread. Next, sprinkle the shredded sharp cheddar cheese on top of the mozzarella, again ensuring even coverage. Finally, finish by generously sprinkling the grated Parmesan cheese over the cheddar. The combination of cheeses will create a melty, gooey, and flavorful topping. Don’t overcrowd the cheese layer too much; you want it to melt evenly and not become too thick.
Carefully place the cheese-topped bread halves onto a baking sheet. You can line the baking sheet with parchment paper for easier cleanup if desired, but it’s not strictly necessary. Place the baking sheet in the preheated oven and bake for 12-15 minutes, or until the cheese is melted, bubbly, and golden brown, and the edges of the bread are crisp and lightly toasted. Keep a close eye on the garlic bread during the last few minutes of baking to prevent burning, as ovens can vary in temperature.
Once the cheesy garlic bread is beautifully golden and bubbly, remove it from the oven. Let it rest for a couple of minutes on the baking sheet before slicing. This allows the cheese to set slightly and prevents it from being too runny when cut. Using a sharp knife or pizza cutter, slice the garlic bread into serving-sized pieces. Serve immediately while it’s hot, cheesy, and utterly irresistible.
