Step 1Heat the oven to 375 degrees. Cut ½ cup (1 stick) of butter into small pieces and freeze.
Step 2Cut up the remaining butter and place in a small skillet over medium heat. When the butter melts, start swirling it in the pan. The butter will sputter while the water cooks out, and the solids will separate. Keep cooking and swirling until the solidss have sunk to the bottom and browned and the butter smells nutty, about 5 minutes. Keep a constant eye on the butter so it doesn’t burn. Pour the butter out into a small bowl, making sure you’ve got all the browned bits.
Step 3In a large bowl, whisk together the flour, baking powder, baking soda and salt. Remove the butter from the freezer and work it into the dry ingredients using your fingers until it resembles very coarse oatmeal with some larger bits of butter. Stir 2 teaspoons of the browned butter into ¾ cup of the buttermilk, add it to the dry ingredients, and stir the dough with your hand, kneading it a little. Add more buttermilk if you need it to make a cohesive dough that leaves the bowl clean.
Step 4Dump the dough out onto a floured surface and pat it into an even disk with smooth edges. Roll out to a thickness of 1/4-inch. Cut the biscuits with a 2-inch cutter and set them, barely touching, on a rimmed baking sheet. Gather up the scraps, form another even disk, and repeat. Brush the biscuits with some more of the browned butter and bake until risen and nicely browned on the top and bottom (lift one to check), 20 to 25 minutes.