Ingredients

  • 4 garlic cloves, divided
  • 1/2 cup (packed) fresh basil leaves
  • 1/4 cup mayonnaise
  • 5 tablespoons extra-virgin olive oil, divided
  • 2 anchovy fillets packed in oil, drained
  • 1 tablespoon fresh lemon juice
  • 4 cups (about 1 1/3 pound) cherry tomatoes
  • 1 small fennel bulb, trimmed, halved, thinly sliced
  • Kosher salt and freshly ground black pepper
  • 1/4 cup dry white wine
  • 1 8-ounce bottle clam juice
  • 3 pounds mixed shellfish (such as littleneck clams, cockles, mussels), scrubbed
  • 2 tablespoons chopped fresh flat-leaf parsley
  • Crusty bread, sliced (for serving)

Method

  • Mince or finely grate 2 garlic cloves and transfer to a blender. Add basil, mayonnaise, 3 tablespoons oil, anchovies, and lemon juice. Puree until smooth. Transfer basil rouille to a small bowl, cover, and chill.
  • Heat remaining 2 tablespoons oil in a large heavy pot over medium-high heat. Add tomatoes and fennel; season with salt and pepper and cook, stirring occasionally, until tomatoes burst, about 10 minutes.
  • Slice remaining 2 garlic cloves and add to pot. Cook, stirring often, until garlic becomes fragrant, about 1 minute. Pour in wine and cook, stirring often, until almost absorbed, about 1 minute. Add clam juice and 4 cups water and bring to a boil. Add shellfish and cook, covered, until opened (discard any that do not open), about 3 minutes. Stir in parsley. Spread basil rouille on bread and serve alongside.