Cook the pasta

• Bring a large pot of salted water to a boil.
• Cook the spaghetti until al dente, then drain, reserving some pasta water.

Brown the sausage

• Heat the olive oil in a large sauté pan over medium heat.
• Add the Italian sausage and cook, breaking it up, until browned.

Build the sauce

• Add the garlic, anchovies and red pepper flakes and cook until fragrant.
• Stir in the cherry tomatoes and cook until they begin to burst.
• Pour in the white wine and simmer to reduce slightly.

Cook the seafood

• Add the clams, cover and cook until they open.
• Add the halibut and shrimp and cook gently until just opaque.

Combine and serve

• Add the drained spaghetti to the pan with a splash of pasta water and toss to coat.
• Season with salt and black pepper, then fold in the tarragon and parsley.
• Serve on a large platter.