1. Begin by cooking the whole wheat penne pasta according to package directions in a large pot of salted boiling water. Once al dente, drain and set aside.
2. In a large skillet, heat the olive oil over medium heat. Add the finely chopped yellow onion, red bell pepper, and green bell pepper. Sauté until the vegetables are soft, about 5 minutes. Then, add the minced garlic and cook for an additional 1 minute. Toss in the andouille sausage and Cajun seasoning, stirring well to combine.
3. Stir in the shredded cooked chicken and allow it to heat through for a few minutes.
4. In a small bowl, whisk together the skim milk and cornstarch until smooth. Pour this mixture into the skillet, adding the chicken broth as well. Stir continuously until the sauce thickens, about 3-5 minutes.
5. Add the cooked penne pasta to the skillet and gently toss to coat the pasta in the creamy Cajun sauce. Remove from heat and mix in the shredded low-fat parmesan cheese until melted and well incorporated.
6. Serve the Skinny Cajun Chicken Pasta hot, garnished with additional parmesan cheese if desired. Enjoy the wonderful burst of flavors!