Preheat fan forced oven to 170C.
Mix dry ingredients in a large bowl until well combined.
Add cubes of butter and golden syrup into a small saucepan. Heat on medium until the butter is melted.
In a small bowl, mix the bicarb of soda with the boiling water and stir. Add this mix into the saucepan of melted butter and golden syrup. The mix will start to foam and increase in volume. Using a spatula, add this wet mix into the bowl of dry ingredients and stir everything together until well combined.
Make roughly 20 balls of dough from this ‘dough’ (about the size of a heaped tablespoon each). Place each ball evenly across 2-3 baking trays lined with baking paper. Lightly press down on each ball to make a disc. They will continue to spread when they bake so allow a 5cm gap between each disc.
Note: the thicker the disc, the chewier your biscuit will be. The thinner the disc, the crispier it will be.
Bake for 10-11 minutes. Check on them around 9 minutes. These biscuits will be darker than your usual ANZAC biscuit because of the brown sugar. Leave the biscuits to cool on the tray. They will firm up more on cooling so take the trays out of the oven just before your desired level of chew. Garnish biscuits with rosemary the moment they come out of the oven. Their temperature will help release the oils in the rosemary and impart the scent into the biscuits. Sprinkle with sea salt flakes.