01 - Line an 8 x 8 inch square baking tin with parchment paper, ensuring some overhang for easy removal.
02 - Arrange a single layer of Tennis biscuits to cover the base of the tin, breaking biscuits to fit snugly.
03 - Whip the cold heavy cream in a large mixing bowl until stiff peaks form.
04 - Stir the caramel treat or dulce de leche until smooth. Gently fold it into the whipped cream until just combined.
05 - Fold the roughly chopped Peppermint Crisp bars into the caramel-cream mixture.
06 - Spread half of the caramel-cream mixture evenly over the biscuit base, then add another layer of biscuits on top.
07 - Spread the remaining caramel-cream mixture over the second biscuit layer and smooth the surface.
08 - Sprinkle the grated or finely chopped Peppermint Crisp bar evenly over the top layer.
09 - Refrigerate for at least 3 hours or until firm.
10 - Lift from the tin using parchment overhang, cut into 12 slices, and serve chilled.