Gluten free baking powder is quick and easy to make and costs less than buying a commercial brand. Just make sure you buy cornflour made from maize rather than the finely milled wheat variety that masquerades as cornflour (don’t get me started on labeling laws!).
1 teaspoon baking soda (bi-carb)
2 teaspoons cream of tartar
1 teaspoon cornflour (corn starch – make sure it’s 100% maize)
Mix together and store in a sealed container in the pantry. Shake before use.