Cook linguine in salted water according to package directions. Save 1/2 cup of cooking liquid and drain. Set aside.
Cut each chicken breast in half horizontally into two thinner pieces. Season with salt, pepper, and 1 teaspoon of dried oregano.
Heat olive oil in a large nonstick skillet over medium-high heat. Add chicken and cook for about 4 minutes per side, or until cooked through. Remove chicken and set aside.
Add a little more olive oil to the pan and cook onion until softened. Add garlic and cook 1 minute.
Add cream cheese and half-and-half. Cook over low heat until cream cheese is melted.
Stir in feta cheese, lemon juice, salt, pepper, spinach, sun-dried tomatoes, kalamata olives, roasted red peppers, and remaining dried oregano.
Combine sauce and cooked pasta in a large bowl and mix together. Sprinkle with parsley and serve.
