In a large Dutch oven, warm 3 tablespoons of olive oil and melt 1 tablespoon of butter over medium-high heat. Add the chopped fennel and diced onion, cooking for about 5 minutes until they soften and become fragrant.

Stir in the minced garlic, dried thyme, paprika, saffron threads, and cayenne pepper. Cook for about 20 seconds.

Pour in a splash of white wine, scraping the bottom of the pot to deglaze. Let it cook for 1 minute.

Gently stir in 4 cups of clam juice or seafood stock, the undrained canned diced tomatoes, and 2 bay leaves.

Bring the mixture to a boil, then lower heat to medium. Allow it to simmer for 8 to 10 minutes.

Season 1 pound of halibut pieces with salt and fresh ground black pepper, then gently add them to the pot. Cover and cook for 2 minutes.

Nestle 12 ounces of cleaned mussels and 1 pound of sea scallops into the broth. Cover and cook for another 3 minutes.

Uncover the pot and add 240 to 280 grams of peeled and deveined shrimp. Cook for an additional 2 to 3 minutes until shrimp turn opaque.

Remove from heat, discard the bay leaves and any unopened mussels. Stir in 2 tablespoons of fresh basil and 1 tablespoon of fresh parsley.

Ladle the bouillabaisse into wide bowls, garnishing with red pepper flakes if desired.