Preheat Your Oven and Prepare Baking Sheet: Preheat your oven to 425°F (220°C). Line a baking sheet with parchment paper.

Combine the Dry Ingredients: In a large bowl, whisk together the flour, sugar, baking powder, baking soda, and salt.

Add the Butter: Scatter the small cubes of cold butter into the flour mixture. Using a pastry blender or your fingertips, cut in the butter until the mixture resembles coarse crumbs.

Add the Sourdough Discard and Buttermilk: Make a well in the center of the flour mixture. Pour in the sourdough discard and the cold buttermilk. Stir until just combined; the dough should be sticky.

Turn Out and Fold the Dough: Turn the dough out onto a floured surface. Gently knead it a few times until it comes together, then pat it into a rectangle. Fold the rectangle into thirds, like a letter, turn it 90 degrees, and pat it down again. Repeat this folding process 3 times. This method will create those beautiful flaky layers in your biscuits.

Cut Out the Biscuits: Pat or roll the dough out to about 1 inch thick. Using a round biscuit cutter, cut out the biscuits and place them on the prepared baking sheet. Try to cut straight down without twisting to ensure the best rise.

Bake: Bake for about 15-20 minutes, or until the biscuits are golden brown.

Cool and Serve: Allow the biscuits to cool for a few minutes on the baking sheet before serving.