Preheat the oven to 375°F. Line a baking sheet with parchment paper.

Sift the dry ingredients into a small bowl. Work the butter into the flour with a fork until the mixture is crumbly. Stir in the jalapeño. Mix in the buttermilk a little at a time, adding just enough so that it comes together into a smooth ball of dough. Do not overwork the dough.

On a lightly floured work surface, roll the dough into a 7-inch round, 1⁄2 inch thick. Using a 1-inch cookie cutter, press out 12 rounds. Reroll scraps to make additional biscuits. Transfer the rounds to the baking sheet. Bake until the tops are golden and the bottoms browned, about 15 minutes. Serve warm.