Preheat oven to 350F. Line two baking sheets with parchment paper and set aside.
In a medium bowl, whisk melted butter and syrup together until smooth. Whisk in boiling water and baking soda. (mixture may bubble a bit) Whisk in brown sugar and vanilla until smooth.
In a small bowl, combine oats, coconut, flour, and salt. Fold into liquid mixture until dough is just combined.
Form dough into 1-in balls and place 2-in apart on prepared baking sheets. (careful, these spread a lot!) Flatten balls very slightly.
Bake anzac biscuits at 350F 12-15 minutes, rotating the pan once halfway through baking, until cookies are a very deep golden brown. (they should be on the darker side than your average cookie) Cool biscuits on pan 10 minutes, then transfer to a wire cooling rack to cool completely. Enjoy!