There was a time when making a coffeecake was a real struggle for me. The deciding factor was buttermilk. I dreaded buying buttermilk, using half a cup and then having a carton rot in my fridge and then..... I stumbled upon this:
Powdered buttermilk! What a great invention! It is so easy to use. Basically, for every 1/4 cup of buttermilk, you add 1 tablespoon of the powder to your dry ingredients and 1/4 cup water to your wet ingredients. It works great. I cannot detect a difference between this product and the liquid version. So from now on, do not be afraid of curdled, soured dairy. Buy this stuff and bake, bake, bake!