Preheat the oven to 400°F (200°C). Using a sharp bread knife, slice the baguette in half lengthwise so you have two long halves with the cut sides facing up. If you prefer pull-apart slices, instead make diagonal cuts ¾ inch apart without cutting all the way through, leaving the base intact.

Make garlic herb butter

In a medium bowl, combine the softened unsalted butter with the minced garlic, chopped parsley, chopped basil (if using), lemon juice, salt, and black pepper. Mix thoroughly until smooth and evenly incorporated. Stir in 1 tablespoon olive oil to loosen the mixture for easy spreading.

Spread mixture on bread

Using a spatula or butter knife, evenly spread the garlic-herb butter over the cut sides of the baguette halves (or into the cuts if you made pull-apart slices). Make sure to get the butter into the ends and any interior cuts so every bite has flavor.

Cheese & Bake

Top with cheeses

Sprinkle the shredded mozzarella evenly over the buttered cut surfaces, covering to the edges. Scatter the grated Parmesan over the mozzarella for a savory finish. If you prefer extra crisping on the top, press the cheese lightly into the butter so it adheres.

Bake until bubbly

Place the prepared halves on a baking sheet lined with parchment or foil. Bake in the preheated oven for 10–12 minutes, until the butter has melted and the cheese is fully melted and bubbly. If you want golden brown, switch to broil (high) for 1–2 minutes watching closely to avoid burning.

Finish & Serve

Garnish and slice

Remove from oven. Sprinkle the top with the remaining 1 teaspoon olive oil (drizzle) or brush lightly for shine, and add red pepper flakes if using. Let rest 1–2 minutes, then slice into portions (if using full-halves, cut crosswise into 1–2 inch pieces).

Serve warm. Garlic cheese bread is best eaten immediately while cheese is gooey. Leftovers can be reheated in a 350°F (175°C) oven for 8–10 minutes for crispness.