In a large skillet over medium heat, cook red onion in 2 tbs. olive oil, stirring occasionally, for 20 minutes, or until onion is soft and caramelized. Add remaining Tbs. olive oil and chicken, and sprinkle with salt and pepper. Cook 15 minutes, or until chicken is cooked through, and remove from heat.
Meanwhile, cook pasta according to package instructions. Drain, reserving 1/2 cup cooking water, and return pasta to pot it was cooked in.
Pour the reserved water back into pot with the pasta, and stir in yogurt until noodles are coated.
Add chicken mixture to pasta, stir, and serve. Enjoy!