Australian Chocolate Slice

Preheat oven to 325 degrees F and line a 9×9-inch baking dish with parchment paper, then lightly grease paper.
For the crust: In a medium-sized bowl, combine flour, coconut, brown sugar, and cocoa powder. Mix in egg, melted butter, and vanilla until just combined.
Transfer the mixture to the prepared baking dish and press into an even layer.
Bake for 20-23 minutes or until baked through the middle.
When bars are about 5 minutes from fully baked, prepare the icing: In a medium-sized bowl, sift together the powdered sugar and cocoa powder. Mix in the melted butter and water until smooth.
Pour icing over bars while they’re still hot out of the oven and quickly spread to the edges to evenly cover.
Allow bars to fully cool and icing to set at room temperature before slicing.