Take butter and cut it up into small cubes. Add butter to a bowl, along with a small handful of flour, and mix the butter so it's fully coated with flour. Add butter to the food processor and pulse a few times to chop it up.
Add flour, baking powder, baking soda, salt and sugar to the food processor and pulse a couple more times to get a crumbly mixture.
Remove the dough from the food processor and add to a large bowl. Add in buttermilk and chopped jalapeño, mixing to fully combine. Knead the dough with your hands for 2 minutes.
On a lightly floured surface, spread out dough to 1/2 inch thick. Using biscuit cutters or circle cookie cutters, cut biscuits. Keep repeating until all dough is used, sometimes re-spreading the dough if needed. You will get 18-20 biscuits.
Put biscuits on greased baking sheet. Bake for 13-15 minutes, or until the bottoms turn slightly brown. Serve and enjoy!
Notes
Note: Freeze butter beforehand, for about an hour. This will allow it to more easily be cut into the flour. If are you in a rush, refrigerated butter will work too.