Add four cups of vegetable broth to a large pot. Break the fettuccine in half to make stirring easier later, and then add it to the pot. Also add the canned tomatoes (undrained), olive oil, frozen spinach, onion (thinly sliced), garlic (thinly sliced), basil, oregano, red pepper, and some freshly cracked black pepper.
Make sure the ingredients are submerged under the liquid, place a lid on top of the pot, and then turn the heat on to high. Allow the pot to come up to a full, rolling boil over high heat then remove the lid and turn the heat down to medium.
Allow the pot to continue to boil over medium heat, without a lid, for 10-15 minutes, or until the pasta is cooked and most of the liquid has been absorbed. Stir the pot every few minutes as it cooks to prevent the pasta from sticking to the bottom, but avoid over stirring which can cause the pasta to become sticky and mushy. The pot must be boiling the entire time.
After the pasta is cooked, crumble the feta cheese over top and serve.
You can also add your favorite meat to this dish. I often will add seasoned hamburger for additional protein.