Preheat the oven to 160°C and line a 20cm x 20cm square tin with baking paper..
Melt together the butter and golden syrup in a saucepan over a low heat.
In a large bowl, combine oats, flour, brown sugar and coconut.
Dissolve the baking soda in the boiling water, add to saucepan.
Combine liquid and dry ingredients.
Press the biscuit mixture into the bottom of the tin and bake in the oven for around 15 mins or until lightly golden brown.
Allow to cool whilst you make the caramel filling.