Preheat the oven to 180°C/350°F (160°C fan), and line 2 large baking trays with baking paper.
Add the butter and golden syrup to the Thermomix bowl and melt for 3 min/70°C/speed 2. Meanwhile, mix the bicarbonate of soda in 1 tablespoon of boiling water. When the 3 minutes is up, and the butter is fully melted, add the bicarbonate of soda mix to the Thermomix bowl and mix for 5 sec/speed 3.
Add the flour, oats, coconut and sugar and mix for 20 sec/reverse/speed 3. The mixture will come together; stir any stranded bits around the sides with a spatula.
Roll the mixture out into walnut-sized balls and place them onto the baking trays, roughly 5cm apart. Flatten each one slightly with the palm of your hand.
Bake one tray at a time for 12-15 minutes. Depending on whether you like your Anzac biscuits soft or crunchy, 12 mins = soft, 15 mins = crunchy. Also, the timing will vary on the oven, so keep an eye on them.
When ready, remove the biscuits from the oven and cool them on the baking tray for 10 minutes. Then, transfer them to a wire rack to cool completely. They will come out of the oven soft but will harden when cooled.
Notes
Storage: Store the Anzac biscuits in an airtight container for up to 2 weeks. They can be frozen for up to 3 months.