Summer Tomato Bouillabaisse with Basil Pouille

Summer Tomato Bouillabaisse with Basil Pouille:

4 garlic cloves, divided

1/2 cup (packed) fresh basil leaves

1/4 cup mayonnaise

5 tbsp extra-virgin olive oil, divided

2 anchovy fillets packed in oil, drained

1 tbsp 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 oz bottle clam juice

3 lbs mixed shellfish (such as littleneck clams, cockles, mussels), scrubbed

2 tbsp chopped fresh flat-leaf parsley

crusty bread, sliced (for serving)

Mince or finely grate 2 garlic cloves and transfer to a blender. Add basil, mayonnaise, 3 tablespoons oil, anchovies, and lemon juice. Purée 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.