In a medium bowl, toss diced chicken with 1 tablespoon of Cajun seasoning and stir to completely coat. Set aside.
Bring a medium pot of water to boil and cook penne according to directions for al dente pasta. Drain and set aside.
In a large skillet (cast iron if you have it), melt 1-1/2 tablespoons of butter and 1 teaspoon of olive oil over medium-high heat.
Add chicken to skillet and cook for 4-6 minutes or until cooked through. Remove chicken from pan and cover.
Turn heat to low and add 1 tablespoon of flour to the pan (you should sill have some butter/oil left in there) and stir/whisk constantly until the flour/butter forms a pasty roux mixture. Do not let this burn, it will only take a minute.
Slowly add 3/4 cup of skim milk while whisking constantly to keep lumps from forming. If lumps do form, just smush them up with a spatula and continue to whisk. Mixture should be smooth.
Add 1/4 cup sundried tomato past, 2 diced green onions, 1/8 teaspoon black pepper, 1 clove of minced garlic, 1/2 teaspoon dried parsley, and 1/4 teaspoon of dried basil. Turn heat up to medium/medium-high and whisk together and cook until mixture thickens.
Add penne, chicken, and 1/4 cup of parmesan to the skillet, and stir to coat.