Start by pounding the chicken breasts to an even thickness if using whole breasts. This ensures they cook evenly and quickly. Cut into bite-sized pieces or thin slices if desired.
In a bowl, season the chicken pieces with Kosher salt and freshly ground black pepper. Make sure every piece is well coated for maximum flavor.
In a large skillet or Dutch oven, heat the olive oil and butter over medium heat. Once the butter is melted, add the diced red onion and sauté until translucent, about 3-4 minutes. Add the minced garlic and Italian seasoning, cooking for about 1 minute until fragrant.
Add the seasoned chicken pieces to the skillet, cooking until browned on all sides, about 5-7 minutes. The chicken does not need to be fully cooked at this stage as it will finish cooking later.
Stir in the halved cherry tomatoes and cook for another 2-3 minutes until they start to soften.
Sprinkle the all-purpose flour over the mixture, stirring to combine. This step helps to thicken the broth later on.
Slowly pour in the chicken broth while stirring to combine. Bring the mixture to a gentle boil.
Add the uncooked orzo pasta to the pot, stirring to ensure it’s evenly distributed. Cover and reduce the heat to a simmer. Cook for about 10-12 minutes or until the orzo is tender and the chicken is cooked through.
Once cooked, remove the pot from the heat. Stir in the fresh basil and sprinkle with shredded Parmesan cheese. Serve immediately, garnished with additional basil and cheese if desired.