Preheat the oven to 170C (150C fan forced).
Line a baking tray with baking paper and set aside.
Place the rolled oats, spelt, chopped macadamias, sugar, coconut and salt in a large bowl and mix together.
Melt the butter and golden syrup in medium saucepan.
Combine the bicarbonate soda and boiling water.
Whilst continuously stirring, pour the bicarbonate soda mixture into the melted butter and golden syrup.
Pour the melted butter mixture into the dry ingredients and mix thoroughly.
Take a dessert spoon of mixture, and press it together in your hands until the mixture forms into rough ball.
Place the ball on the lined tray and flatten lightly until the biscuit is approximately 1.5cm thick. Make the biscuit slightly thicker if you want chewy biscuits.
Repeat with the remainder of the mixture.
Bake for 20 minutes, or until the biscuits are golden brown.
Cool on a rack, then transfer to an airtight container for storage.