Sauté onion in hot olive oil until tender and golden, about 5 minutes. Add the garlic and sauté for 30 seconds.
Stir in the tomatoes with their juices, broth, wine, tomato puree, ½ tablespoon dry oregano, cayenne pepper, smoked paprika and the red pepper flakes. Reduce the heat to medium-low and cook for 15 - 20 minutes, uncovered, until the sauce is lightly thickened and the flavors have blended.
Add the squid, cover, reduce the heat to low and cook for 25 - 30 minutes until very tender. Stir in the remaining oregano.
Meanwhile cook spaghetti in lots of boiling water according to the manufacturer’s instructions.
Drain and stir into the warm sauce. Toss thoroughly until the pasta is fully coated with sauce.