Heat the olive oil in your large skillet over medium heat. Add the diced chicken breast, seasoning lightly with salt and pepper. Cook for about 5-6 minutes, stirring occasionally, until the chicken is browned on all sides but not fully cooked through. Remove the chicken and set aside.
In the same pan, add the diced onion and sauté for 3-4 minutes until translucent and fragrant. Stir in the minced garlic and cook for another 30 seconds, being careful not to burn it.
Add the orzo pasta directly into the pan with the onions and garlic. Stir to coat the pasta with the flavorful oil and aromatics. Pour in the chicken broth and the entire can of diced tomatoes with their juices. Sprinkle the Italian seasoning, and add salt and pepper to taste. Stir everything well.
Return the browned chicken to the pan, submerging it gently in the liquid. Bring the mixture to a gentle boil, then reduce heat to a simmer. Cover the pan with a lid and cook for about 10-12 minutes, or until the orzo is tender and the chicken is cooked through.
Remove the lid and sprinkle the shredded mozzarella and grated Parmesan cheese evenly over the top. Cover again and let it sit off the heat for 2-3 minutes, allowing the cheese to melt beautifully.
Finish with fresh basil leaves scattered on top for a burst of color and flavor. Serve immediately and enjoy the comforting goodness of your homemade One-Pot Chicken Parmesan Orzo.
