Roast garlic: separate cloves without removing skin. Place in a small dish with 1-2 tablespoons water and drizzle with olive oil. Bake covered at 350F for 30-35 minutes until soft. Squeeze garlic out of skins into a bowl.
Blend roasted garlic with 1/2 cup broth until smooth and set aside.
In a large pot, saute onions until translucent.
Add garlic/broth mixture and remaining broth to the pot.
Bring to boil and add cod. Cook for 10 minutes and reduce heat to simmer.
Puree spaghetti squash with 1 cup broth mixture from pot.
Add pureed squash, clams and shrimp to the pot.
Cook for 5-10 minutes until clams and shrimp are fully cooked.
Serve as is or over a bowl of raw spinach.