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 flour mixture. Using a pastry cutter or 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 flour mixture.
05 - Pour cold buttermilk over mixture and gently fold with a fork just until dough comes together. Be careful not to overmix.
06 - Turn dough onto lightly floured surface. Pat gently into a 1-inch thick rectangle. Do not knead.
07 - Using a floured 2.5-inch biscuit cutter, press straight down through dough without twisting to cut rounds. Gather scraps and gently press together to cut additional biscuits.
08 - Place biscuits on prepared baking sheet, spacing 1 inch apart. Brush tops with milk or cream if using.
09 - Bake for 14 to 16 minutes until biscuits are risen and golden brown on top.
10 - Cool briefly on baking sheet for 2 to 3 minutes, then serve warm.