(Short) Macadamia Shortbread

A quick version of our macadamia shortbread. Ingredients: 220g chilled butter, chopped 2/3 cup caster sugar (can be reduced to 1/2 cup) 2 cups plain gluten free flour – extra 1/2 cup plain gluten free flour (as needed) 1/2 cup rice flour 1 teaspoon vanilla extract (or vanilla essence) 1 egg 300g whole (or pre-chopped) raw or roasted unsalted macadamias