Heat a large pot over medium heat and drizzle in olive oil. Add diced boneless skinless chicken breasts seasoned generously with Cajun seasoning, salt, and pepper. Sauté for 5-7 minutes, stirring occasionally, until the chicken is nicely browned and cooked through. Remove the chicken from the pot and set aside.

In the same pot, add a bit more olive oil if needed, and toss in diced onions and minced garlic. Sauté for 2-3 minutes until the onions become translucent and softened. If desired, stir in the diced bell pepper and cook for another 2 minutes.

Add the orzo pasta to the pot, stirring to coat it well with the aromatic mixture. Pour in chicken broth and heavy cream, mixing thoroughly. Bring to a boil, then reduce heat to low and let it simmer for 10-12 minutes, stirring occasionally.

Once the orzo is cooked, return the browned chicken to the pot. Stir in grated Parmesan cheese until melted into the sauce. Taste and adjust seasoning if needed.

Dish out the One Pot Cajun Chicken Alfredo Orzo into bowls. Garnish with freshly chopped parsley, if desired. Serve immediately.