Preheat the oven to 375°F (190°C) and line a baking sheet with parchment paper.
Prepare the garlic butter: In a bowl, mix softened butter, minced garlic, chopped parsley, salt, black pepper, and red chili flakes (if using).
Slice the bread: Cut the loaf in half lengthwise and place both halves on the baking sheet.
Spread the butter mixture: Evenly spread the garlic butter over the cut sides of the bread.
Sprinkle cheese: Top with grated Parmesan cheese.
Bake: Place in the oven for 8-10 minutes until golden and crispy.
Broil (optional): For extra crispiness, broil for 1-2 minutes (watch closely to avoid burning).
Slice & serve: Cut into pieces and serve warm.