Step 1

Melt butter in a large braising pan over medium heat. Cook onions and garlic in melted butter, stirring occasionally with a wooden spoon, until onions are softened, 5 to 7 minutes.

Step 2

Stir chicken broth, diced tomatoes, wine, water, basil, thyme, oregano, red pepper flakes, and bay leaves with the onion and garlic. Place a cover on the braising pan and cook mixture at a simmer until the tomatoes are softened and the broth flavorful, about 30 minutes.

Step 3

Fold cod, shrimp, scallops, clams, and mussels into the broth mixture; bring to a boil, reduce heat to low, return cover to pan, and continue to simmer until the clams open, 5 to 7 minutes.