Preheat oven to 450 degrees F. Line a small sheet pan with parchment paper. Set aside.
In a large bowl, whisk flour with sugar, salt, baking powder, and baking soda. Alternatively, you can pulse everything in a food processor.
Add the COLD cubed butter (freeze the butter beforehand). Using a pastry blender, cut the butter into smaller pieces, incorporating it with the flour until you get pea-sized pieces. You may also need to use your fingers to work the butter into the flour. If using a food processor, pulse a few times until you get pea-sized pieces.
Gradually add the buttermilk and incorporate using a rubber spatula until you get a shaggy and crumbly dough. If using a food processor, pulse a few times until a shaggy and crumbly dough forms. The pieces of butter should be visible in the dough.
Transfer the shaggy dough onto a working surface. Bring everything together and press the dough to form a 1-inch thick rectangle. Fold it over, from short end to short end, and press it down again to re-form a 1-inch thick rectangle. Tip: I like to transfer the dough to a large piece of parchment paper and use it to press the dough - it’s much easier, less messy, and helps keep the dough cold.
Cut into 9 biscuits using a 3-inch round biscuit cutter. Note: Do not twist the biscuit cutter as you press it down, as this can seal the edges and prevent the biscuits from rising and forming flaky layers.
Arrange biscuits in the prepared sheet pan, about 1 inch apart (biscuits tend to rise taller when you place them close together). Brush the tops with some heavy cream. Bake at 450 degrees F for 15 to 16 minutes, or until risen and golden brown. Enjoy!