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 blended.
03 - Add cold butter cubes to the flour mixture. Using a pastry cutter or your fingertips, work the butter into the flour until it resembles coarse crumbs with some pea-sized pieces remaining.
04 - Stir in grated Gruyere cheese and chopped sage until evenly distributed throughout the mixture.
05 - Pour in cold buttermilk and mix gently with a fork just until the dough comes together. Be careful not to overmix.
06 - Turn dough onto a lightly floured surface. Pat into a rectangle about 1-inch thick.
07 - Using a floured 2.5-inch biscuit cutter, cut out rounds by pressing straight down without twisting. Gather scraps and repeat until all dough is used.
08 - Place biscuits on the prepared baking sheet, spacing them 1 inch apart. Brush tops with milk or cream if desired.
09 - Bake for 14 to 16 minutes until biscuits are golden brown on top.
10 - Let biscuits cool slightly on the baking sheet, then serve warm.