In a large bowl, crush the canned tomatoes and their juices using clean hands. Set aside.
Heat a large skillet over medium heat and add olive oil. Once hot, stir in the drained seafood and cook until done, about 3-5 minutes.
Gently remove seafood from the skillet and set aside to drain any liquid.
In the same pan, add ghee or butter and cook diced onion until soft, about 8 minutes. Stir in minced garlic and cook for an additional minute.
Mix in tomato paste and red pepper flakes. Cook for an additional 2 minutes.
Add crushed tomatoes to the skillet, season with salt and pepper, and let simmer for 10 minutes.
While sauce simmers, cook spaghetti according to package instructions until al dente, reserving about ¼ cup of pasta water before draining.
Off heat, gently stir the cooked seafood into the sauce. Adjust seasonings if needed.
Combine the al dente spaghetti with the sauce, adding reserved pasta water as needed. Toss to coat.
Garnish with fresh parsley and lemon juice. Serve immediately.