Line a slice tray with baking paper.
Crush the biscuits until a fine crumb.
In a large bowl melt the butter, stir in the condensed milk and the flesh of 2 passionfruit, mix until combined.
Stir in the biscuit crumbs and coconut, mix until well combined.
Press into the lined slice tray until firmly packed and smooth on the top.
In a small bowl stir the softened butter and the flesh of the remaining passionfruit with the icing sugar, gradually adding enough boiling water to make a thick icing.
Spread icing over slice and refrigerate until set approximately 2 hours.
Cut into desired size pieces and enjoy.
