Instructions:
- Melt chocolate in a double boiler, stirring occasionally.
- In a separate bowl, whip the heavy cream until it forms stiff peaks.
- Stir in the butter and vanilla extract until fully incorporated.
- Slowly pour the chocolate into the cream mixture and fold until combined.
- Spoon the mousse into individual serving cups and chill until set.
- Drizzle with truffle oil before serving.
Note: This dessert is best enjoyed while wearing a beret and sipping absinthe.