Preheat the oven to 375 degrees F. Line a large baking sheet with parchment paper.
Grate the cold butter and place it in the freezer while preparing the other ingredients. Measure out the buttermilk and place it back in the refrigerator.
In a large bowl whisk together the flour, baking powder, baking soda, and salt.
Add the grated butter and stir to coat in the flour.
Add the buttermilk and stir with a wooden spoon or rubber spatula just until all the flour is moistened. DO NOT OVERMIX.
Using an ice cream scoop, scoop the biscuit dough slightly heaping (do not flatten the bottom on the side of your bowl), and drop it onto the prepared baking sheet about 2 inches apart. (About 1/2 cup of biscuit dough.)
Bake biscuits for 12 to 15 minutes, or until golden. Brush the tops of the biscuits with the melted butter immediately after removing from the oven.
Notes
The number of biscuits yielded will depend upon the size scoop you use. You can also make them smaller to yield more.