Add plain flour, rolled oats, desiccated coconut, rapadura sugar, salt and rosemary leaves to a large bowl. Mix well.
Heat butter and golden syrup in a small heavy bottomed saucepan on medium-low heat until the butter is melted. Reduce heat to low.
Mic bicarbonate of soda in the boiling water in a small bowl. Add the soda-water mixture to the butter mixture. The mixture will start foaming and increasing in volume. Remove from heat immediately and mix well.
Add this bubbly butter mixture to the dry ingredients in the bowl. Mix and knead the biscuit dough with your hand.
Roll one tablespoon of dough in the palm of your hands. Flatten to a 1cm high disc shape. Pace on the prepared baking sheet. Repeat with remaining dough, placing the flattened biscuits 3cm apart on the tray.
Bake in the preheated oven for 15-18 minutes depending on how golden and crispy you want them. The longer you bake, the crispier and browner they get.
Remove from the oven and cool on wire rack. They will harden up as they cool. Store in an air-tight lidded glass container in a cool corner of your kitchen. They last for up to a week.
Notes
Rapadura sugar – Rapadura sugar is unrefined palm sugar. You can substitute with coconut sugar or brown sugar.Golden Syrup - Golden syrup is a deep amber coloured treacle, a form of inverted sugar syrup made by boiling down sugar in water and lemon juice. Substitutes include corn syrup or molasses or a mix of both. Honey has a distinct taste so it doesn't make the best substitute. Make Golden Syrup At Home - Boil 3 cups raw sugar and 2 tablespoons brown sugar in 1 1/4 cup water and 2 tablespoons lemon juice until a thick syrup is formed. This keeps well in the fridge for a few weeks.The biscuits will get softer as the days go by but you can easily crisp them up in a pre-heated oven for 5 minutes.