Preheat your oven to 450°F (232°C) and place a rack in the middle position. Line a baking sheet with parchment paper. For maximum success, chill your mixing bowl and pastry cutter in the freezer for 10 minutes before starting.
In your chilled bowl, whisk together the flour, baking powder, baking soda, sugar, and salt until thoroughly combined.
Add your cold butter cubes to the flour mixture. Using a pastry cutter or two forks, cut the butter into the flour until the mixture resembles coarse crumbs with some pea-sized pieces remaining. Work quickly to keep the butter cold.
Make a well in the center of your mixture and pour in the cold buttermilk. Using a wooden spoon or rubber spatula, gently fold the ingredients together just until the dry ingredients are moistened. The dough will look shaggy and slightly sticky.
Turn the dough onto a lightly floured surface and pat into a rough rectangle. Using the "envelope method," fold the dough like a business letter (in thirds) and then once more into thirds the other way to create layers.
Pat the folded dough to about 1-inch thickness. Using a 2.5-inch round biscuit cutter, press straight down without twisting. Place the biscuits on your prepared baking sheet with sides touching for higher rise or 1 inch apart for crispier sides.
Let the cut biscuits rest for 10 minutes to allow the gluten to relax.
Brush the tops with melted butter and bake for 15-18 minutes until the tops are golden brown. For even coloring, rotate the pan halfway through baking.
Let rest for 5 minutes before serving to allow the interior to set while maintaining warmth.