Simply Shellfish: Basque-Style Rice With Cockles

Ingredients

• 2 pounds cockles or manila clams
• 4 tablespoons extra-virgin olive oil, plus more for finishing
• 2 cloves garlic
• 1 dried red guindilla pepper
• 2 flat-leaf parsley sprigs plus 1/4 cup loosely packed fresh flat-leaf parsley leaves
• 1/4 cup dry white wine
• 1/4 cup manzanilla sherry
• About 2 cups mussel stock or fish stock
• 1/2 Spanish onion
• kosher salt
• 1 cup Bomba rice