03In a medium skillet set over medium heat, melt the butter. Add olive oil, onion and raisins and cook, stirring, until onion is soft, about 3 minutes. Add all the rice and cook, stirring, until heated through. Stir in the chopped chervil and tarragon, season with salt and pepper and remove from heat. Spoon mixture into the baked squash shells, mounding it slightly. Garnish with chervil sprigs and serve.