01 -
In a large mixing bowl, whisk together the flour, sugar, baking powder, baking soda, and salt.
02 -
Add the cold, cubed butter to the dry ingredients. Use a pastry cutter or your fingertips to work the butter into the flour until the mixture resembles coarse crumbs with some pea-sized pieces.
03 -
Pour in the sourdough discard and the cold buttermilk, and gently stir. If the dough is too dry, add one tablespoon of extra buttermilk at a time, until the dough comes together but is not overly sticky.
04 -
Turn the dough out onto a floured surface. Gently press it into a rectangle, then fold it in thirds like a letter. Rotate the dough 90 degrees, roll it out again, and repeat the folding process 2-3 more times to create layers.
05 -
Roll the dough into a rectangle about 1 inch thick. Using a sharp knife or bench scraper, cut the dough into squares. Do not twist the knife to ensure clean edges for maximum rise.
06 -
Place the biscuits on the prepared baking sheet, spacing them about 1/2 inch apart. Place in the freezer for 30 minutes while you preheat your oven to 425°F.
07 -
Brush biscuits with milk or heavy cream and sprinkle with flaky sea salt or sugar. Work fast as the liquid will freeze. Bake for 17-19 minutes or until golden brown on top.