Preheat oven to 450°F. Line a large baking sheet with parchment paper or a silicone baking mat and set aside.
In a large mixing bowl, whisk together the flour, baking powder, baking soda, sugar, and salt until well combined. Add the in the cubed cold butter and cut into the dry ingredients using a pastry cutter (you may also use a food processor for this step) until you have small pea sized pieces of butter. Pour the cold buttermilk into the mixture and gently work it together until the dough starts to come together.
Scoop the dough onto a lightly floured surface and gently work it together with your hands. Pat the dough into a rectangle and fold it in thirds. Turn the dough, gather any crumbs, and flatten back into a rectangle. Repeat this process two more times.
Place the dough onto a lightly floured surface and pat it down into a 1/2-inch thick rectangle (make sure to measure!). Using a floured 2.5-inch biscuit cutter, cut out the biscuits. Continue to gather any scrap pieces of dough, patting it back down to 1/2-inch thickness, and cutting it until you have 12 biscuits. I suggest trying to get as many as you can the first time, as you continue to work the dough the biscuits won't be quite as good.
Arrange the biscuits on the baking sheet touching each other. Brush the top of each biscuit with a little bit of buttermilk.
Bake at 450°F for about 15-17 minutes or until lightly golden brown. Remove from the oven and brush with melted butter if desired. Allow to cool for a few minutes, serve, and enjoy!