In a large bowl, drizzle olive oil over chicken breasts and sprinkle with Cajun seasoning, garlic powder, onion powder, smoked paprika, salt, and black pepper. Coat thoroughly.

Heat a skillet over medium heat and sear each side of the seasoned chicken for 2-3 minutes until browned.

Layer sliced bell peppers, onion, and minced garlic over the seared chicken in the slow cooker.

Pour diced tomatoes and chicken broth over the chicken and vegetables, scraping any browned bits from the skillet.

Cover and cook on low for 4-5 hours or high for 2-3 hours until the chicken is tender.

Remove the chicken, shred it using two forks, and return it to the slow cooker, stirring it into the sauce.

Stir in heavy cream and grated Parmesan cheese until well combined and creamy.

Cook the penne pasta according to package instructions until al dente, drain, and set aside.

Add the drained pasta to the slow cooker, stir gently, cover, and heat on low for 15-20 minutes.

Serve hot, garnished with chopped parsley if desired.