01 - Preheat oven to 400°F. Grease a 12-cup muffin tin or line with paper liners.
02 - In a large mixing bowl, whisk together all-purpose flour, baking powder, baking soda, salt, chili powder, and garlic powder.
03 - Add cold butter cubes to the flour mixture. Use a pastry cutter or fork to incorporate butter until the mixture forms coarse crumbs.
04 - Fold in shredded cheddar, diced jalapeños, minced garlic, and chopped chives if using.
05 - Pour in buttermilk and gently mix until just combined. Dough should be sticky—do not overmix.
06 - With a large spoon or cookie scoop, divide dough evenly among muffin cups, rounding each portion into balls.
07 - Bake for 16 to 18 minutes, or until golden brown and a toothpick inserted in the center withdraws clean.
08 - Remove from oven and immediately brush tops with melted butter. Sprinkle with chili flakes if desired.
09 - Allow to cool for 5 minutes before removing from pan. Serve warm.