While you're chopping the few ingredients that go into this dish, make sure you put a large pot of water on to boil. When it comes to a boil and you add the pasta, begin heating your oil as the whole dish takes about 10 minutes to come together. I couldn't find any whole wheat fettuccine, so I used linguine instead, but I think this would be good with a shorter pasta like rigatoni or fusilli as well.
Add the onions and garlic and cook for about 5 minutes, stirring occasionally. Add the red peppers and cook another minute or two until everything is warm.
Move the onion and pepper mixture into the food processor along with the chicken stock/broth and 2/3 of the feta. Process until you have a sauce with a nice smooth texture.
Drain the pasta, reserving about 1/2 cup of the pasta water to thin out the sauce if necessary (I forgot to do this and ended up adding a few tablespoons of chicken broth instead). Toss the pasta with the sauce and serve with the extra feta and some chopped parsley. When you consider the amount of time it takes to prepare this dish, it's really pretty impressive. Pair with some good bread or a salad (or both) and you've got a perfect weeknight pasta dish. Enjoy!