Line the base of a 20cm spring form tin with baking paper and set aside.
Place shortbread and butter into TM bowl and mill 15 sec/speed 7. Scrape down sides of bowl and repeat if necessary.
Press into prepared tin and refrigerate.
Place cream cheese, milk, vanilla, lime juice and zest into TM bowl and blend 30 sec/speed 6.
Stir gelatin into hot water to dissolve a little.
Add gelatin mixture to TM bowl and blend 30 sec/speed 5–6.
Pour into prepared base.Cover and allow to set in fridge.
To make sour cream topping, place sour cream and vanilla into TM bowl.
Stir gelatin into hot water to dissolve a little. Add gelatin mixture to TM bowl and blend 30 sec/speed 5–6.
Spread the sour cream mixture on top of the lime filling quickly and return to the fridge to set completely before serving in wedges with whipped cream or sour cream on the side.