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Preheat oven to 450 degrees with racks set in the upper and lower thirds of the oven. Line two baking sheets with parchment paper; set aside.
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In a large bowl, whisk together flour, baking powder, sugar, salt, and baking soda. Add butter and using a pastry cutter or your fingers, work the butter in until the mixture resembles coarse crumbs, with some larger pieces still remaining. Add herbs, if using, and stir to combine.
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Make a well in the center and gradually add buttermilk, stirring with a fork or wooden spoon until large clumps form. Turn mixture out onto a lightly floured work surface, and using lightly floured hands, knead two or three times just until a dough forms.
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Pat dough into an 8-by-8-inch square. Using a sharp knife, cut 2-inch square biscuits, or use a 2-inch round cutter, and transfer to prepared baking sheet, spacing 2 inches apart. Brush tops with buttermilk. Transfer to oven and bake until golden brown, about 12 minutes.