Substitutions I Use in Baking

Because of Sam's sensitivites to cornstarch, tapioca flour, potato starch, eggs, milk, and butter, I've had to come up with substitutions for those things in my baking. Here is what I do:

For baking powder I mix 2 parts of cream of tartar with 1 part baking soda. So if a recipe calls for 1 tsp of baking powder, I mix together 2 heaping 1/4 tsp of cream of tartar with 1 heaping 1/4 tsp of baking soda and then add it to the ingredients to make 1 tsp total.

For a binder in my rice flour baking I use 1 or 2 tbsp of Betty Crocker's Potato Buds because it's more of a whole potato than just the starch. The old version of Betty Crocker's Potato buds do not have citric acid in them like the "new and improved" version that is out now. I have a big box of the old version left that I am hoping will last me a very long time.
UPDATE 1/17/11: I just discovered that Whole Foods carries their store-brand instant mashed potatoes that are just potatoes and nothing else. Yay!

For eggs, I used to use EnerG Egg Replacer, but then Sam's starch sensitivity developed, so I just stopped using eggs altogether. I add a little more oil to my recipes or a jar of baby food for the moistness. My homemade baking powder or baking soda and vinegar works nicely to add lightness and height to my baked goods.

For a milk substitution I just use water or I add a jar of baby food and water to give it a little nutrition.

For butter in baking I use safflower or canola oil and salt as the replacement. On toast, we drizzle olive oil and salt.