Preheat oven to 400 degrees.
Combine flour, salt, baking powder, baking soda,
and sugar in a bowl.
Cut butter into small pieces.
Add butter to flour mixture. If using a food processor, pulse the butter and flour mixture until you have pea-sized crumbs, or use a pastry cutter. If you have neither a food processor or pastry cutter, use your hands to break the butter with your fingers until you have pea-sized lumps combining with flour as you go. Make sure to work quickly so that your body heat doesn't warm the butter.
Gradually add the buttermilk, tossing with a fork to incorporate. Knead the mixture a few times in the bowl until the dough just starts to form (mixture will look dry). Turn the dough out onto a clean surface.
Work the dough into a rectangle roughly 1 inch thick. Using a knife or bench scraper, cut the dough into three pieces. Stack the pieces on top of one another, adding any loose dry bits of dough between the layers. Press down to flatten.
Use your hands (do not use a rolling pin) to create a 1 inch thick rectangle. Using a knife or bench scraper, cut the rectangle in half to make two square biscuits.
Transfer biscuits to a parchment lined baking sheet and freeze for 10 minutes. Bake at 400 degrees for 20-22 minutes, or until lightly golden on top.
If desired, brush with melted butter immediately after removing from oven. Serve warm, and enjoy!