In a large pot, cook the pasta according to the package directions until it is al dente. Drain and set aside.
While the pasta is cooking, begin browning the ground turkey in a large skillet over medium heat.
After the meat has browned for 4 minutes, add the diced onion. Stir and sauté the ground turkey and onion until the turkey is no longer pink and the onions are translucent.
Add the tomato sauce and the taco seasoning and stir well. Bring the taco-flavored sauce mixture to a boil, then reduce heat and simmer for 10 minutes. (Pasta should be almost done cooking)
Add the cream cheese, stirring until it is completely melted. Add the cooked pasta, toss it in the sauce, and remove from heat.
When serving, top pasta with optional taco toppings: lettuce, tomatoes, green onion, shredded cheddar cheese, green chiles, cilantro, and sour cream.