Line a 28cm x 18cm lamington tin with aluminium foil. Cover base of tin with 12 wafers. Trim where necessary so wafers fit base perfectly. Remove from tin and cut remaining 12 wafers to match.
Place chocolate and butter in top of a double saucepan and melt over simmering water. Spread base of tin with half the chocolate mix.
Arrange 12 of the prepared wafers over chocolate. Refrigerate.
Combine condensed milk, butter (extra) and golden syrup in saucepan. Stir constantly over medium heat until mixture begins to stick and bubble on base of pan. Continue to stir a further 3 minutes then stir in peanut butter.
Spread caramel evenly over wafers in tin then arrange the final 12 wafers on top.
Spread wafers with the remaining chocolate mix.
Refrigerate 30 minutes or until chocolate has set. Stand at room temperature for 20 minutes before cutting. With a sharp knife cut into squares, then each square into a triangle.