Preheat the oven.
Preheat your oven to 425°F. Line a baking sheet with parchment paper.
Combine the dry ingredients.
In a food processor or large bowl, combine the flour, baking powder, baking soda, garlic powder, and salt.
Cut in the cold butter.
Add the cubed butter. If using a food processor, pulse briefly about 10–12 times, stopping when the mixture resembles coarse crumbs with some pea-sized pieces of butter remaining.
If mixing by hand, use a pastry cutter, fork, or your fingertips to work the butter into the flour. Keep the butter cold and avoid blending it into a completely smooth mixture.
Add the buttermilk and cheese.
Transfer the mixture to a bowl if using a food processor. Pour in the cold buttermilk and gently stir. About halfway through mixing, add the shredded cheddar.
Mix just until a soft, shaggy dough forms. Use your hands briefly if needed, but do not knead or overmix.
Shape the biscuits.
Scoop the dough into rounded mounds and place them on the prepared baking sheet. Keep them loosely shaped rather than rolling or packing them tightly.
Lightly brush the tops with extra buttermilk.
Bake.
Bake for 12–15 minutes, or until the tops are golden and the centers are baked through. Larger biscuits may need a few extra minutes.
Brush with garlic parsley butter.
Stir together the melted butter, garlic powder, and chopped parsley. Generously brush over the biscuits while they are still warm, then serve.