Make Basil white chocolate ganache: Place white chocolate in a heatproof bowl set over a saucepan with water over medium heat. Melt white chocolate, stirring. Put basil leaves in a heavy-duty ziplock bag then pour in melted chocolate. Press out all the air and seal. Place bag in a pot of water at 115 degrees for 1 to 2 hours. Transfer chocolate to a large glass bowl. Heat cream in a small saucepan over medium-high heat, stirring, until it is just below the boiling point. Add cream to bowl with chocolate and gently mix with a spatula. Strain mixture through a fine-mesh sieve into another bowl. Pour mixture into a siphon. Add 2 charger cartridges and allow mixture to chill for 2 hours.
Make Passion fruit blanket: Put puree in a saucepan over medium-high heat and bring to a boil. In a small bowl, mix together the sugar and pectin then add to puree. Whisk for about 1 minute. Strain through a small sieve or tea strainer onto a silpat and dehydrate for 3 - 4 hours at 53 degrees F in a dehydrator or at the lowest temperature in a conventional oven for 1 - 2 hours.
Make Pistachio chestnut sponge: Blend all ingredients together and strain through a fine mesh sieve. Place mixture in a whipped cream dispenser (siphon) and insert two charger cartridges. Allow to rest 40 minutes. Dispense into a round microwavable container and place it in the microwave at medium power for 1 to 1 minute 30 seconds, until set.
Assemble dish: Dispense white chocolate onto serving dish to form a 1-inch tall mound, take a piece of the passion fruit blanket and place it on white chocolate foam. Press so blanket fits to contour of foam. Take a piece of the pistachio sponge and place next to foam. Put a couple passion fruit pastilles, dots of cassis sauce and orange blossom gel around plate. Using tongs, carefully arrange herb blossoms, salted black beans and roasted barley to create a "garden."