Preheat an oven. Line a rimmed baking sheet with parchment paper, then place the baguette halves cut side up.
In a medium saucepan, add unsalted butter. Set over medium heat. When the butter is mostly melted, add anchovies, garlic cloves, crushed red pepper flakes. Cook. The mixture will smell incredible. Remove from the heat, then stir in chopped parsley and kosher salt.
Set the broiler to high, then place the garlic bread. Sprinkle with flaky sea salt and more cheese, if wanted, then enjoy immediately!