Preheat your oven to 150°C (130°C fan assisted) and line a couple of large baking trays with greaseproof paper.
In a medium sized pan, melt the butter with the sugar, syrup and zest. You want the butter to have melted and combined but you don't want the mixture to boil.
Mix together all of the dry ingredients in a large mixing bowl.
Pour the syrup and butter mixture over the dry ingredients, mixing well until all of the dry ingredients are coated.
Transfer the mixture to the prepared baking trays, making sure they're well spread out and in one single layer on each tray.
Place the trays in the oven, baking for 10 minutes undisturbed.
Remove from the oven and turn the mixture in each tray. Return to the oven and keep checking every 5 minutes.
The granola will be done when the mixture has turned a golden brown colour. Be very careful not to overcook. It will likely still seem a bit soggy when you take it out, but it will crisp up as it cools.
Allow to cool completely in the trays and transfer to an air-tight container once cooled.