Preheat your oven to 425°F (220°C). This high heat is essential for achieving those fluffy, golden biscuits.
In a large mixing bowl, combine the 3 cups of all-purpose flour, baking powder, baking soda, and salt. Whisk together until evenly mixed.
Add the cold, cubed butter to the flour mixture. Using a pastry cutter or fork, cut the butter into the flour until the mixture resembles coarse crumbs with small pea-sized pieces of butter throughout.
Make a well in the center of the flour mixture and pour in the cold buttermilk. Gently stir with a wooden spoon or spatula until just combined. Be careful not to overmix; a few lumps are okay.
Lightly flour your work surface and turn out the dough. With floured hands, gently knead the dough a few times until it comes together, being careful not to overwork it.
Pat the dough into a rectangle about 1-inch thick. If desired, roll it out with a rolling pin. Using a biscuit cutter or a glass, cut out rounds and place them on a baking sheet lined with parchment paper. Gather any scraps, knead gently, and cut out more biscuits.
Brush the tops of the biscuits with melted butter for extra flavor. Bake in the preheated oven for 12-15 minutes, or until golden brown on top.
Once baked, remove the biscuits from the oven and let them cool for a few minutes. Serve warm with your favorite toppings or fillings, and enjoy!