Preheat oven to 160 degrees celsius (fan-forced). Grease a 22cm loose-bottomed tin and set aside.
Melt the butter in the Thermomix for 3 minutes, 80 degrees, Speed 2 (or until melted). Add the biscuits and crush for 5 seconds, Speed 8. Scrape down the sides of the bowl and repeat for a further 5 seconds.
Firmly press the mixture into the base and sides of the prepared tin and bake for 10 minutes. Remove from oven and allow to cool.
Place the sweetened condensed milk, lime juice, eggs and lime zest into a clean and dry Thermomix bowl and mix for 45 seconds, Speed 4. Scrape down the sides and mix for a further 45 seconds or until thick and creamy.
Gently pour the liquid into the prepared base and bake for 15 minutes or until set.
Allow to cool in the fridge for a minimum of 4 hours (preferably overnight). Serve with whipped cream and extra grated lime zest.