Step 1

Preheat oven to 450ºF (232ºC). Line a baking sheet with parchment paper or a silicone baking mat.

Step 2

Whisk together the buttermilk and sourdough starter in a small mixing bowl or liquid measuring cup until it's completely combined.Freeze the mixture as you make the biscuit dough.

Step 3

Mix together the dry ingredients in a large mixing bowl.You can grate the cheddar cheese directly into the bowl.

Step 4

Grate the frozen butter using the large holes of a box grater directly into the mixed dry ingredients.Use a fork or whisk to distribute the butter throughout the mixture so the butter is coated in flour.

Step 5

Pour the cold buttermilk mixture on top of the dry ingredients. As you pour, use a fork to bring the biscuit dough together.At first, the biscuit dough will be dry but will gradually start to form clumps as it's brought together.Knead the dough a few times in the bowl until it comes together into a largely cohesive but still shaggy dough. Add a teaspoon of buttermilk at a time if the dough is still too dry.

Step 6

Transfer the biscuit dough onto a floured work surface and pat down into a circle about 1.5 inches thick.Use a floured 2.5-3" biscuit or cookie cutter to cut out 8-10 biscuits. Cut the biscuits straight down without twisting to not seal the edges of the biscuits. With any scraps, reform and cut out more biscuits.

Step 7

Space the biscuits on the prepared baking sheet and freeze the biscuits for 10 minutes.This quick freeze will help the biscuits rest and chill so they rise well.

Step 8

Brush the tops of the biscuits with additional buttermilk and flaky salt.Bake the biscuits at 450ºF (232ºC) for 15 minutes until the tops are golden brown.Sourdough biscuits are best enjoyed warm! And no one's stopping you from brushing them with some melted butter and more fresh chives.