Heat oven to 350°F and line a large baking sheet with foil.
Slice the loaf in-half lengthwise, and place each half cut-side up on the prepared baking sheet.
In a small saucepan set over LOW heat, combine butter, garlic and crushed red pepper flakes. Bring the mixture to a low boil and boil 1 minute. Do NOT allow the garlic to brown. Remove from the heat.
Pour the butter through a mesh strainer and into a heatproof bowl.
Add 1-tablespoon parsley and mix well.
Spread or brush all except 4 tablespoons butter mixture over the bread and sprinkle with salt.
Bake the bread at 350°F, on the middle rack of the oven, for 10 minutes.
Remove the bread from the oven and set the temperature to BROIL.
If using Parmesan cheese, sprinkle it onto the bread.
Return the bread to the oven and broil 1-2 minutes or until the bread is toasty and golden and the cheese bubbles slightly. *Watch closely so the bread doesn’t burn.
Remove from the oven and sprinkle with the remaining ½ tablespoon of parsley. Allow the bread to cool 1-minute before slicing.
Use leftover butter mixture for a dipping sauce, if desired.
Serve immediately.