01 - Preheat oven to 425°F. Line a baking sheet with parchment paper.
02 - In a large bowl, whisk together flour, baking powder, baking soda, salt, and pepper until well combined.
03 - Add cold butter cubes to the flour mixture. Using a pastry cutter or your fingertips, cut butter into flour until mixture resembles coarse crumbs with some pea-sized butter pieces remaining.
04 - Stir in grated Gruyere cheese and chopped sage until evenly distributed throughout the mixture.
05 - Pour cold buttermilk over the mixture and mix gently with a fork just until dough comes together. Do not overmix.
06 - Turn dough onto a lightly floured surface. Pat gently into a 1-inch thick rectangle.
07 - Using a floured 2.5-inch biscuit cutter, cut out rounds by pressing straight down without twisting the cutter. Gather scraps and repeat to form additional biscuits.
08 - Place biscuits on the prepared baking sheet, spacing them 1 inch apart. Brush tops with milk or cream if desired for a golden finish.
09 - Bake for 14 to 16 minutes until tops are golden brown and biscuits are cooked through.
10 - Cool biscuits slightly on the baking sheet, then serve warm.