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. Using a pastry cutter or your fingertips, work butter into flour mixture until it resembles coarse crumbs with some pea-sized pieces remaining.
04 - Stir in grated Gruyere and chopped sage until evenly distributed.
05 - Pour in cold buttermilk and mix gently with a fork just until dough comes together. Do not overmix.
06 - Turn dough onto a lightly floured surface. Pat into a 1-inch thick rectangle. Using a floured 2.5-inch biscuit cutter, cut straight down without twisting. Gather scraps and repeat.
07 - Place biscuits 1 inch apart on prepared baking sheet. Brush tops with milk or cream if desired. Bake 14 to 16 minutes until golden brown.
08 - Cool slightly on baking sheet, then serve warm.