Preheat oven to 180 C (160 C fan forced). Grease 20 cm x 30 cm (8 inch x 12 inch) rectangular pan, line base with baking paper, extending paper 5 cm (2 inches) over long sides.
Beat butter and sugar in small bowl with electric mixer until light and fluffy, stir in sifted flour and ginger. Spread mixture over base of pan.
Meanwhile, make topping, Stir sifted icing sugar, butter and syrup in small saucepan over heat until butter is melted. Stir in nuts and ginger.
Spread hot topping over cold base. Cool slice in pan before cutting.