In a saucepan, add the sweetened condensed milk, butter, golden syrup and Gregg's Ground Ginger. Stir over medium heat until almost boiling, it will thicken during heating.* Pour the filling over the shortcake base, carefully spreading to cover the base. Return to the oven and bake for a further 12 minutes. Remove from the oven and cool in the tin. Carefully lift out and place on a wire rack.