Preheat your oven to 425°F (220°C). Line a baking sheet with parchment paper.

In a large mixing bowl, whisk together the all-purpose flour, baking powder, baking soda, granulated sugar, and salt until well combined.

Add the very cold, cubed butter to the dry ingredients. Using a pastry blender or two forks, cut the butter into the flour mixture until it resembles coarse crumbs with some pea-sized pieces of butter remaining. Avoid overworking the mixture.

Pour the very cold buttermilk into the flour-butter mixture. Stir gently with a spoon or your hands until just combined and a shaggy dough forms. Be careful not to overmix; some dry spots are okay. If the dough is too dry, add an additional tablespoon or two of buttermilk, one at a time.

Lightly flour a clean surface. Turn the dough out onto the floured surface. Gently pat the dough into a rectangle about 3/4 to 1-inch thick. Fold the dough in half, then pat it down again to about 3/4 to 1-inch thick. Repeat this folding and patting process 2-3 more times to create flaky layers. This is crucial for flaky biscuits.

Using a 2.5-inch biscuit cutter, cut out biscuits by pressing straight down (do not twist). Place the cut biscuits onto the prepared baking sheet, leaving about 1 inch between them. Gather the scraps, gently press them together without overworking, and cut out any remaining biscuits.

Bake in the preheated oven for 12-15 minutes, or until the tops are golden brown and the biscuits are cooked through. Baking time may vary depending on your oven.

While the biscuits are still hot, brush their tops with melted butter.

Serve warm with your favorite toppings like jam, honey, or gravy. Enjoy!