Place softened butter and caster sugar in a mixing bowl and mix together until light and creamy. Add lemon zest to the creamed butter and sugar and mix well. (This can be done either with an electric mixer or by hand).
Add vanilla and egg and beat mixture to combine.
Gradually add sifted self raising flour and lemon juice to the mixture and stir until the mixture forms a smooth dough.
Stir through the chopped macadamia pieces and mix well.
Place dough in the fridge to chill for 5- 10 minutes before making the cookies. This makes the sough much easier to work with and will help stop cookies from spreading too much during baking.
Using a teaspoon, make small balls of biscuit dough and roll in icing sugar (confectioner's sugar/powdered sugar) to coat.
Place dough balls on the lined baking trays, leaving space between each to allow for spreading. Flatten the top of each ball slightly with the back of a spoon.
Place trays in the oven and bake for 12 minutes or until cookies start to turn golden brown.
Remove cookies from the oven and allow to cool on the trays for 5 minutes before transferring to a wire rack to cool completely
Notes
Cookies will keep in an airtight container for up to 5 days. Suitable to freeze (either baked cookies or unbaked cookie dough prior to rolling in icing. powdered sugar).