Directions
Preheat oven to 425 degrees F.
Line a baking sheet with a silicone baking mat or parchment paper. Whisk flour, baking powder, salt, and baking soda together in a large bowl. Cut butter into flour mixture with a pastry blender until the mixture resembles coarse crumbs, about 5 minutes. Make a well in the center of butter and flour mixture. Pour in 3/4 cup buttermilk; stir until just combined. Knead dough onto a floured work surface, mixing thoroughly. Roll dough on a floured surface to about 1/2 inch thick. Cut out 12 biscuits using a 2 1/2-inch round biscuit cutter. Transfer biscuits to the prepared baking sheet. Press an indent into the top of each biscuit with your thumb. Brush the tops of biscuits with 2 tablespoons buttermilk. Bake in the preheated oven until browned, about 15 minutes.
Ingredients
2 cups all-purpose flour
2 teaspoons baking powder
1 teaspoon salt
1/4 teaspoon baking soda
7 tablespoons unsalted butter, chilled in freezer and cut into thin slices
3/4 cup cold buttermilk
2 tablespoons buttermilk for brushing