3 Tablespoons unsalted butter
2 carrots, finely chopped
1 onion, finely chopped
1 celery stalk, finely chopped
1 small russet potato, peeled and finely chopped
2 pounds small shrimp, peeled and deveined
2 cups fish stock
2 cups cream
1/2 Tablespoon dried thyme
1 bay leaf
Salt and white pepper
1 Tablespoon fresh chervil or parsley