Homemade Baking Powder
Have you ever been caught out with the oven preheating but no baking powder in the house (like I did last week!)? When you know how to make your own it's not a problem!
Simply sift together 2 tablespoons cream of tartar, 1 tablespoon bicarbonate of soda and 1 tablespoon cornflour then give it a good stir or shake it well in a jar until evenly combined. Store this homemade version in an airtight jar and use it in your recipes in the same quantities as you would commercially made baking powder.
Incidentally, making your own means you can also avoid the aluminium-based acidifying agents (like sodium aluminium sulphate and sodium aluminium phosphate) sometimes used in commercial baking powder.