Method

• To make mousse, heat butter in a small saucepan over medium heat. Cook garlic and thyme for 2 minutes to soften without colouring. Add wine and simmer until almost all evaporated. Stir in cream and heat to almost simmering. Remove from heat and stir in parmesan.
• Cool cream for 10 minutes, then strain through a sieve into a bowl. Chill for at least 1 hour.
• To make plums, heat oil in a large frying pan and sear the cut side of plums until golden brown. Scatter onion and chilli around plums, then drizzle over vinegar and honey. Give the pan a shake and cook for 1 minute. Carefully turn over plums and simmer until liquid reduces to a thick syrup. Cool to room temperature.
• To make parmesan crisps, place a second frying pan over medium heat. Sprinkle parmesan evenly over base of pan and cook until cheese is melted and lightly browned. Remove from heat and cool for 2 minutes. Transfer parmesan crisp to a wire rack with a spatula and cool completely. Break into shards.
• Whip cream mixture until it holds its shape (don’t overbeat). Use a large metal spoon to quenelle mousse onto four plates. Surround mousse with salad leaves and spoon over plums and syrup. Garnish with walnuts and parmesan crisps, then serve.