Preheat the oven to 425F. Butter the bottom and sides of a 10 inch cast-iron skillet.
In a medium sized mixing bowl, sift together the flour, garlic powder, and onion powder. Use a pastry blender or two forks to cut the cubed butter into the flour until it resembles cornmeal. Mix the cheddar cheese into the crumbs.
Make a well in the center and add the buttermilk. Mix the buttermilk into the dry ingredients gradually, using a fork. Mix until just fully moistened.
Use a 4 ounce ice cream scoop to divide the dough, placing the biscuits side by side in the skillet.
Mix together the melted butter, parsley, and garlic salt. Lightly brush the tops of the biscuits, reserving some of the herbed butter for the tops at the end of baking.
Bake for 15 to 20 minutes, or until cooked through and golden. Broil at the end of baking to brown the tops further, if desired.
Brush with the reserved herbed butter and serve.
Make certain that all of your ingredients are cold. If you feel that your ingredients are warming up during the biscuit making process, stick your biscuit dough in the refrigerator for a few minutes to cool back down.