Preheat the oven to 425°F. Line a sheet tray with parchment paper. 

Grate 8 tablespoons of the butter or dice it very small and place it in the freezer for 15 minutes. Add the buttermilk to the freezer during this time as well.

In a large bowl stir together the flour, baking powder, sugar, salt, and baking soda. Add the butter and cut it in with a pastry cutter or you can use two forks. The mixture should appear crumbly with no larger than pea-sized pieces of butter.

Pour in ¾ cup of buttermilk (if any of the buttermilk started to freeze, just break it up with a fork). Stir until combined, mixture will be crumbly, with some of the flour not fully mixing in.

Lightly dust a clean work surface with more flour. Pour out the dough mixture and work it with your hands to form a ball. 

Roll the dough out into ½ inch thick rectangle. Fold ? of one side over the center. Fold the other ? on top. Roll it out into a ½ inch rectangle again and fold the same way. Repeat 1 more time.

Do the tri-fold one last time but this time roll out the dough into a 1-inch thickness. Using a 2 & ½ inch biscuit cutter, cut out the biscuits. Place the biscuits slightly touching onto the parchment-lined sheet tray.

Roll the scraps back into a ball and roll it out again to cut more biscuits. Keep doing this until you have 8 biscuits. 

Brush the tops of the biscuits with the remaining 1 tablespoon of buttermilk. Bake for 13-15 minutes until puffed up and the tops are golden brown.

While the biscuits are cooking, melt the remaining 2 tablespoons of butter.

Immediately brush the tops of the biscuits with the melted butter. Let cool slightly and serve.