In a large mixing bowl, whisk together the flour, baking powder, baking soda, sugar, and salt until well combined. Add the cold butter to the bowl and use a pastry cutter or fork to cut the butter into the dry ingredients, until the mixture resembles rough gravel.
Pour the cold buttermilk into the mixture and stir gently until a dough starts to form.
Transfer the dough onto a lightly floured surface and bring it together with your hands. Pat the dough into a rectangle and fold the ends in over each other. Turn the dough 90 degrees and pat back into a rectangle. Repeat the folding process two more times.
Finally, pat the dough into a 1/2-inch thick rectangle. Cut out the biscuits with a 2 1/2” biscuit cutter. Do not twist the biscuit cutter, just press down and pull up. Cut out as many biscuits as you can, then gather the remaining dough, press back to 1/2” thick and cut more.
Freeze the biscuits for 15 minutes while you preheat the smoker to 300° F(150°C).
Arrange the biscuits in a cast iron pan. Brush the tops with buttermilk.
When the smoker is ready, place the cast iron pan on the grate and smoke the biscuits for 45 minutes or until golden brown.
Let cool for 5 before serving.