Prep. Preheat the oven to 425F. Line a baking tray with a piece of parchment paper.
Make the dough. Add the flour, baking powder, and 1/2 teaspoon garlic salt to a large bowl; whisk to combine. Cut the butter into the dry ingredients until it’s coarsely incorporated, and there are some pieces the size of peas. Make a well in the center and add the discard and milk. Use a fork to mix the wet ingredients into the flour mixture, switching to your hands when it starts to form a shaggy dough. Fold in the shredded cheddar (it’ll look like too much cheese, but it’s not).
Shape. Divide the dough into 4 equal pieces and roll each into a ball. Place the dough balls spaced evenly apart on the prepared tray. Sprinkle the tops with the remaining 1/4 teaspoon garlic salt.
Bake. Bake until the biscuits are puffed and golden, about 13 to 15 minutes.
Finish. Brush the melted butter on top and enjoy.
Notes
Garlic Salt Substitute: If you prefer, you can omit the garlic salt and instead use 3/4 teaspoon garlic powder + 1/2 teaspoon salt. Mix it up and use 1 teaspoon in the biscuits and sprinkle 1/4 teaspoon on top.
Buttermilk: If you don’t have buttermilk, you can use 1/4 cup whole milk and add 1 teaspoon fresh lemon juice or 3/4 teaspoon white vinegar.
Storage and Freezing: Once cooled to room temperature, pop these into an airtight container and store them at room temperature for up to 2 days or in the fridge for up to 5 days. To freeze, store them in an airtight container layered between pieces of parchment paper for up to 3 months.
Reheating: If these have been in the fridge a few days or if they’ve been frozen, I like to reheat them to re-crisp the outside and make the inside tender again. You can reheat them in a 350F oven for 5 to 10 minutes, in a 350F toaster oven for about 5 minutes, or in a 325F air fryer for 3 to 5 minutes.
Sourdough Discard Weight: The weight of sourdough discard can vary greatly. For consistency’s sake, here we’re assuming 1/4 cup of sourdough discard (100% hydration; stirred down; 6 days old or younger) weighs 65 grams.