1 cup (120g) King Arthur Unbleached All-Purpose Flour
2 teaspoons baking powder
3/4 teaspoon salt
8 tablespoons (113g) unsalted butter, cold
1 cup (227g) sourdough starter, unfed/discard*
Preheat the oven to 425°F, with a rack and baking stone in the upper third. Grease a baking sheet, or line it with parchment.
Cut up cold butter into small cubes.
Combine the flour, baking powder, and salt. Work the butter into the flour until the mixture is unevenly crumbly. Hand mixing is ideal, but a stand mixer won’t mash the butter well enough - will need some work with a spoon by hand.
Add the starter, mixing gently until the dough is cohesive. Stand mixer stir setting works well, about 5 minutes.
Turn the dough out onto a lightly floured surface (a piece of parchment works well), and gently pat it into a 6” round about 1”-thick.
Use a sharp 2 3/8” biscuit cutter to cut four rounds, cutting them as close to one another as possible. Gently push and pat the scraps into a 2 1/2” x 5” rectangle. Cut two more biscuits. Push and pat the remaining scraps into a 1”-thick biscuit; it’ll be slightly smaller than the others.
Place the biscuits onto the prepared baking sheet, leaving about 2” between them; they’ll spread as they bake.
Bake the biscuits in the upper third of your oven for 20 to 23 minutes, until they’re golden brown.
Remove the biscuits from the oven, and serve warm.