Preheat and prepare pan. Preheat your oven to 450°3F/230°C. Line a cookie sheet with parchment paper or silicone baking mat, or you can bake these in a cast iron, or lightly greased round cake pan.
Combine dry ingredients. In a mixing bowl, whisk together flour, baking powder, sugar, and salt.
Cut in butter. Using your fingertips, two knives, or a pastry blender, cut the butter into the dry ingredients until the butter is pea-sized. Stir in cold buttermilk and sourdough discard, and stir to combine.
Knead the dough. Scrape the dough onto a lightly floured surface And bring the dough together gently with your hands. Pat the dough down into about a 1/2-inch thickness and fold the dough in half (or thirds like a book). Repeat this process 3 more times.
Cut out the biscuits. Pat the dough into a 3/4-inch to 1-inch thick circle. Cut out the biscuits using a 2 ½ to 3- inch biscuit cutter. Press the scraps together and cut out remaining biscuits. Try to handle the dough as little as possible. I usually get about 8 biscuits (I like mine on the thicker side.)
Bake the biscuits. Arrange biscuits onto either parchment lined cookie sheet, in a round baking dish or in a cast iron. Place them close together edges touching for fluffy pull apart biscuits. For crispier edges space them apart from each other. Top with a sprinkle of turbinado sugar. Bake for 15 minutes until golden brown.