Warm 1 tablespoon of olive oil in a large pot over medium heat until shimmering, then add the chicken for sautéing.
Add 1 lb of diced chicken, seasoning it with 1 tablespoon of Cajun seasoning, salt, and pepper, and cook until golden brown, about 5-7 minutes.
Remove the browned chicken and set aside, leaving flavorful bits in the pot.
Add 1 cup of diced onions and 2 minced garlic cloves in the same pot. Cook until fragrant, about 2-3 minutes.
Stir in 1 cup of diced bell pepper, if using, and sauté until onions are translucent.
Mix in 1.5 cups of orzo pasta, 4 cups of chicken broth, and 1 cup of heavy cream, and bring to a gentle boil.
Reduce heat to low, cover, and let simmer for 10-12 minutes, stirring occasionally until orzo is tender.
Stir in the cooked chicken and 1 cup of grated Parmesan cheese until creamy and well combined.
Ladle the warm orzo mixture into bowls and garnish with fresh parsley. Serve hot.
Notes
For a lighter finish, swap heavy cream for half and half but expect less richness. Add a splash more broth or cream if the sauce gets too thick when reheating.