Prepare the Dough. In a large mixing bowl, combine the flour, sugar, baking powder, baking soda, and salt. Cut the cold butter into small cubes and add it to the dry ingredients. Use a pastry cutter or your fingers to work the butter into the flour mixture until it resembles coarse crumbs. Gently fold in the fresh blueberries.
Add the Buttermilk. Make a well in the center of the dry ingredients and pour in the buttermilk. Using a spatula or wooden spoon, gently stir the mixture until a soft dough forms. Be careful not to overmix, as this can result in tough biscuits.
Shape the Biscuits. Turn the dough out onto a lightly floured surface. Pat it into a rectangle about 1 inch thick. Use a sharp knife or a biscuit cutter to cut the dough into squares or rounds, as desired.
Bake Until Golden. Place the shaped biscuits on a parchment-lined baking sheet, leaving some space between each one. Brush the tops with a little extra buttermilk for a golden finish. Bake in a 400F preheated oven for 16-20 minutes, or until the biscuits are puffed and golden brown.
Serve and Enjoy. Once baked, transfer the biscuits to a wire rack to cool slightly before serving. These biscuits are best enjoyed warm, either on their own or with a pat of butter and a drizzle of honey.