I learned to use arrowroot flour during my Ayurvedic training back in the early 90’s. It is an excellent gluten free thickener for things like chicken pot pie and helps make bread and cakes light and fluffy.
I use cacao powder in everything from gluten free cookies to cakes to brownies. High in antioxidants, It is one of my favorite gluten free ingredients. If you like chocolate check out my cacao powder recipes.
Wikipedia defines shortening as any fat that is solid at room temperature. Some fats are better than others, though, and when it comes to gluten-free baking, I prefer Spectrum organic vegetable shortening.