Preheat oven to 190C. Mix the butter and flour until well incorporated. Sift flour, baking powder and ginder into the mix. Combine into a dough.
Knead the dough for a couple of minutes. Line the baking tray with baking paper and press the dough into it. Ensure it's flat.
Bake the base for about 20 minutes or until lightly browned.
While the slice bakes, combine all icing ingredients in a small pot and combine over a low heat. When the butter is melted and combined, remove from the heat.
When the base is cooked, remove from the oven and drizzle the icing over while it's still hot. Leave to set before slicing and storing.
Notes
Also great with crystallized ginger sprinkled over the icing and set in.