Place the Chocolate Shortbread base and butter into the Thermomix bowl and blend 6 sec/speed 6.
Press into a lined 18 x 28cm baking tin. Place into freezer while you prepare the filling.
Place the condensed milk, EVOO, creme de menthe, peppermint oil and vanilla into a clean dry Thermomix bowl and blend 10 sec/speed 5. Scrape down sides of bowl and make sure it is well combined. Repeat blending if necessary. Remove from bowl and set aside.
Without cleaning, add cream to the Thermomix bowl and whip 20-40 sec/Butterfly/speed 4 or until soft peaks form. Add to the peppermint mixture and fold cream through with a spatula by hand.
Spread onto the base, top with the Peppermint Crisp bars and place into freezer.
Serve in squares with or without more whipped cream.