Preheat the oven to 450°F. Line a sheet pan with parchment paper and set aside.
In a liquid measuring cup, measure the buttermilk, then place in the freezer to get extra cold while you work on the next steps.
1 ¼ cups buttermilk
In a medium skillet, melt the butter over medium heat. Allow it to cook until it's barley turning golden brown and foamy, stirring occasionally. Once barely golden, add the sage and garlic. Continue cooking until the butter is a true golden brown and fragrant, about 60-90 seconds. Pour it into a bowl to help it start cooling (be sure to scrape up all the brown bits and sage from the pan!). 10 tablespoons salted butter, ¼ cup (about 4 oz) fresh sage, 1 tablespoon garlic
While the butter is cooling, whisk together the flour, sugar, baking powder, salt, and black pepper in a large bowl.
2 cups all purpose flour, 1 tablespoon granulated sugar, 1 tablespoon baking powder, 1 teaspoon kosher salt, ¼ teaspoon ground black pepper
Once the butter is warm but not piping hot, remove the cold buttermilk from the freezer. Add the browned butter to the milk and mix well with a whisk or fork. It should form small curdles or clumps.
Pour the wet ingredients into the dry ingredients and stir well with a rubber spatula until the dough is just combined (don't overmix). Using a ¼ cup scoop, scoop the biscuit dough into 10-12 biscuits onto the prepared sheet pan.
Bake for 13-15 minutes, or until golden brown on the bottom and cooked through. Allow to cool on the rack for 5-10 minutes. Then brush with extra melted butter (if desired) and serve warm.
2-3 tablespoons melted butter to brush on top