In a large bowl, coat the skinless, boneless chicken breasts with olive oil and sprinkle generously with Cajun seasoning, garlic powder, onion powder, smoked paprika, salt, and black pepper.

Heat a skillet over medium heat and add the seasoned chicken breasts. Sear the chicken for approximately 2-3 minutes on each side until golden brown.

Carefully transfer the chicken to the slow cooker. Arrange the pieces evenly at the bottom of the pot.

Layer the sliced bell pepper, chopped onion, and minced garlic directly over the chicken in the slow cooker.

Pour the diced tomatoes along with their juices and the chicken broth over the chicken and vegetables.

Cover the slow cooker with its lid and set it on low for 4-5 hours, or on high for 2-3 hours.

Once the chicken is cooked and tender, remove it from the slow cooker and shred it using two forks.

Stir in the heavy cream and grated Parmesan cheese to the slow cooker. Mix well until the cheese melts and blends into a creamy sauce.

While the sauce is forming, cook the penne pasta according to package instructions until al dente, usually about 8-10 minutes.

Add the drained pasta to the slow cooker and stir to combine everything thoroughly. Cover the slow cooker again for an additional 15-20 minutes.

Once heated through, serve the Crock Pot Creamy Cajun Chicken Pasta hot, garnished with freshly chopped parsley.