Bring a large pot of water to a boil. Once the water comes to a boil, add a generous amount of salt and cook the fettucine to al dente.
Place a small saucepot over medium-low heat and melt the butter. Stir in flour with a wooden spoon and cook for about one minute.
Whisk in the milk and bring it to a bubble, then reduce the heat to low. Season with salt, pepper and nutmeg. When sauce is thick enough to coat the back of a spoon, turn off heat and reserve.
Heat a large nonstick skillet over medium heat with the EVOO. Add tuna, celery, onion, artichokes and peas. Cook for 5-7 minutes or until heated through.
Drain pasta and add to the pan with the tuna mixture. Pour in the cream sauce and mix everything together until fully incorporated.
In a small bowl, combine thyme, parsley, garlic and lemon zest. Sprinkle over tuna mixture and serve.