Preheat your oven to 450 degrees F
Grease a cast iron skillet, or line a baking sheet with parchment paper
In a bowl mix together
2 Cups all-purpose flour
2 teaspoons baking powder
1 teaspoon kosher salt
¾ teaspoon baking soda
In a separate bowl mix together
1 Cup active/recently fed sourdough starter
½ Cup buttermilk
Into the separate flour mixture grate in and stir
½ cup butter, frozen
Add in the sourdough starter mixture and mix with a wooden spoon until a dough starts to form
Pour dough onto lightly floured counter and knead for a few minutes until the dough comes together
Use a rolling pin to flatten dough to 1 1/2 inches thick
Use a biscuit cutter or mason jar lid to cut out thick biscuits
Place in cast iron pan or on baking sheet
Bake in oven for 15-18 minutes until golden brown and cooked through