1.Make peanut praline. Place nuts on baking-paper-lined oven tray. Stir sugar and the water in small saucepan over heat, without boiling, until sugar dissolves. Bring to the boil, boil, uncovered, without stirring, until golden brown. Pour mixture over nuts, leave to set at room temperature. Break praline into small pieces.
2.Beat butter and sifted icing sugar in small bowl with electric mixer until light and fluffy, beat in peanut butter.
3.Spread half the peanut butter mixture over four wafers. Top each with another wafer, spread remaining peanut butter mixture over the top of each sandwich. Top with remaining wafers to make four triple-decker wafer sandwiches. Refrigerate 1 hour.
4.Dip tops of sandwiches into chocolate, sprinkle with praline. Refrigerate until set.
5.Using serrated knife, cut wafer sandwiches crossways into four.