Pat chicken pieces dry and toss with 1 tablespoon of Cajun seasoning. Heat olive oil in a large, heavy-bottomed pot over medium-high heat. Add seasoned chicken and cook for 5-6 minutes until golden brown and cooked through. Remove chicken and set aside on a plate.

In the same pot, add diced onion and bell pepper. Cook for 3-4 minutes until vegetables start to soften and smell fragrant. Stir in minced garlic and remaining Cajun seasoning, cooking for another 30 seconds until aromatic.

Add orzo pasta to the pot and stir for 1-2 minutes to toast the pasta until lightly browned.

Pour in chicken broth, scraping up any browned bits from the bottom. Bring to a boil, then reduce heat to medium-low and simmer for 10-12 minutes, stirring occasionally, until orzo is tender and most liquid is absorbed.

Stir in heavy cream, diced tomatoes, and cooked chicken. Let everything warm through for 2-3 minutes. Remove from heat and fold in Parmesan cheese until melted and creamy. Garnish with sliced green onions before serving.