After reading the last few pages of this thread yesterday I was determined to make the Ultimate Butter Cake right away. I thought I had milk, but all I had was cream and buttermilk. So after a quick search, I discovered that when substituting buttermilk for cow's milk in baked goods, using one cup as the base measurement for milk, it's a one to one subsitute for the milk, but you need to add 1/2 tsp baking soda and substract 2 tsp baking powder from the required amount in the recipe. Anway, I made the cake, using Ling's topping and substituting the buttermilk, as instructed above. Although I understand from the conversation that the substitution may dramatically alter the original, I gotta tell you this is one fabulous cake. Or, rather, two! Wow. ← Devlin, Thanks for letting me know! I've been baking like crazy lately and in the past week I made the crumbcake variation and the original butter cake with a chocolate frosting - both were excellent! You should visit Sarah's website too - there's TONS of info on there and an ASK SARAH forum where you can get answers to any of your cake questions...it's a great place to pick up a lot of great tips!