I've decided to make some brownies from a recipe I've found but it calls for buttermilk, which I don't have. Atm I am sharing a vehicle and I don't have it at my disposal, and won't for the next few days (good thing I had no plans, right?). I only have what's here at the house, which is everything save for the buttermilk. Is there any sort of substitute I can use, or a mix of this and that, that will come close? Would regular milk work? Thanks!