Preheat your oven to 375°F (190°C).
In a mixing bowl, combine the softened butter, minced garlic, chopped parsley, salt, black pepper, and red pepper flakes (if using). Mix well until the garlic is evenly distributed throughout the butter.
Slice the French baguette in half lengthwise, and place the halves cut side up on a baking sheet.
Spread the garlic butter mixture generously over the cut sides of the bread using a spoon or a spatula.
For extra crispiness, wrap the bread in aluminum foil, leaving the cut sides exposed.
Place the baking sheet in the preheated oven and bake for about 15 minutes, or until the edges are golden brown and the butter has melted.
Remove the garlic bread from the oven and let it cool for a minute. Cut them into individual slices if desired, and serve warm.