Preheat oven to 200°C and turn on ice cream machine to chill.
For the Peanut Butter Ice Cream, whisk all ingredients together in a medium bowl until combined.
Pour mixture into the pre-chilled ice cream machine and churn according to manufacturer’s instructions. Once frozen, transfer ice cream to the freezer until needed.
For the Biscuit Crumble, line a baking tray with baking paper. Whisk all dry ingredients together in a medium bowl. Stir in melted butter and mix until well combined.
Spread mixture out onto the pre-lined baking tray and press down to make an even layer. Place tray into the oven, then reduce oven temperature to 170°C. Bake until golden brown, about 6-7 minutes.
Remove tray from oven and use a fork to crumble into small chunks. Return tray to the oven to dry out, about 2-3 minutes. Remove from the oven and set aside to cool.
For the Whisky Caramel, make a dry caramel by heating the sugar in a saucepan over medium heat, swirling the pot regularly, until deep golden brown in colour. Remove from the heat and slowly whisk in water and whisky until well incorporated. Return to a low heat and simmer until the liquid has reduced by about half and a thin caramel has formed. Remove from heat and season with salt. Set aside to cool slightly.
For the Warm Chocolate Ganache, heat cream in a small saucepan over medium heat until warm. Meanwhile, place chocolates into a microwave safe bowl and heat in microwave, in 30 second bursts, stirring in between, until fully melted. Whisk cream into the bowl of melted chocolate until smooth.
While still warm, pour chocolate cream mixture into an iSi gun and charge with two N2O charges, shaking well after each charge. Set aside.
To serve, scatter Biscuit Crumble into the base of four shallow serving bowls. Dispense some Warm Chocolate Ganache into the centre of the Biscuit Crumble then top with a scoop of Peanut Butter Ice Cream. Serve with Whisky Caramel on the side.