8 minutes and then reduce the oven temperature to 350 (177c) (do not open the oven door or remove the muffins, just leave them in and reduce the temperature) and bake another 15 minutes, or until tops are just beginning to turn golden brown (if you are using a 12-count muffin tin rather than jumbo-sized, these will not need to bake as long. start checking your muffins after 7-8 minutes on 350f (177c).
*if you don't happen to have buttermilk, you can use this substitute: pour 1 1/2 teaspoons lemon juice or vinegar into a measuring cup and then fill up to the 1/2 cup line with regular milk. stir well 