Prepare the ingredients. Dice the onion. Seed and dice the bell peppers. Mince the garlic. Grate the Parmesan cheese. Cut the chicken breast into bite-sized pieces.
Warm the olive oil in a large skillet over medium-high heat. Add the chicken pieces and sauté for 4-5 minutes, until the chicken is opaque on all sides. Stir in one tablespoon of Cajun seasoning, and cook for 1-2 minutes more. Remove the chicken from the pan and set aside.
Add the diced onion and pepper to the pan. Sauté for a few minutes, until the veggies are crisp-tender. Add the minced garlic and the orzo to the pan, and toast the orzo for 2-3 minutes, stirring constantly so it does not stick to the bottom of the pan. Return the chicken to the pan with the toasted orzo.
Add the chicken stock to the pan, and bring it to a low simmer. Reduce to medium heat, and let the orzo simmer uncovered until almost all of the chicken stock is absorbed (about 10 minutes). Stir it frequently so that it does not burn to the bottom of the pan.
When almost all the chicken stock is absorbed, add the half-and-half. Cook another few minutes, stirring frequently, until almost all the half and half is absorbed and the orzo is cooked al dente. If the orzo is still not cooked enough, and the liquid is fully absorbed, add a little extra water or chicken stock as needed until the orzo is cooked as you like it.
Reduce to low heat, and stir in the fresh-grated Parmesan cheese until melted. Add the baby spinach, and stir until it is well incorporated into the creamy orzo. You can turn the heat off at this point - the residual heat of the pasta will finish wilting the spinach.
Taste the orzo and finish seasoning to taste. Add additional Cajun seasoning if desired (we usually add a couple more teaspoons). Add salt, if needed. Some cajun seasoning blends already contain salt, so you may not need any. I added 1 teaspoon kosher salt to my orzo.
Garnish with some fresh parsley and serve!