Cook penne pasta according to package directions, drain, and set aside.
Coat chicken breast pieces with cajun seasoning.
Heat olive oil in a large skillet over medium-high heat. Add seasoned chicken and cook 6-8 minutes until golden and cooked through.
Remove chicken from skillet and set aside.
Add butter to skillet. Once melted, add onion, red bell pepper, jalapeno, garlic, salt, and pepper. Cook 3-5 minutes until vegetables soften and onions are translucent.
Sprinkle flour over vegetables and stir until flour is absorbed.
Gradually pour in chicken broth while stirring constantly to avoid lumps. Stir in heavy cream and bring to a low boil.
Reduce heat to medium-low and simmer 2-4 minutes until sauce thickens.
Stir in parmesan cheese until fully melted and incorporated.
Add pasta and cooked chicken to the skillet. Toss gently to coat pasta evenly with sauce. Remove from heat and serve.