Heat the olive oil in a large pot or Dutch oven over medium heat. Add the onion and fennel and cook for 6 to 8 minutes, stirring occasionally, until soft and just turning gold.

Add the garlic and red pepper flakes and cook 1 minute, until fragrant.

Pour in the white wine, scraping up any browned bits, and simmer 3 minutes, until the sharp smell of alcohol cooks off.

Stir in the crushed tomatoes, stock and bay leaf. Bring to a simmer and cook, partially covered, for 20 minutes, until the broth thickens slightly and tastes rounded rather than sharp.

Season the broth with salt and pepper; remove the bay leaf.

Raise the heat so the broth is at a steady simmer, then add the mussels. Cover and cook 4 to 6 minutes, until the shells open; discard any that stay closed.

Add the shrimp and cod and cook, uncovered, 4 to 5 minutes, until the shrimp turn pink and the cod flakes easily with a fork.

Taste the broth one more time and adjust the salt.

Ladle into wide, shallow bowls, making sure each one gets a share of mussels, shrimp and cod.

Scatter with parsley and serve immediately with crusty bread for the broth.