Heat olive oil in a large skillet or sauté pan over medium-high heat.
Add the chicken pieces and cook for 5-6 minutes, stirring occasionally, until the chicken is browned and cooked through. Remove the chicken from the pan and set aside.
In the same pan, add the chopped onion and cook for 3-4 minutes until softened.
Add the minced garlic and cook for 30 seconds until fragrant.
Add the orzo pasta to the pan and stir to coat it with the oil and onion mixture.
Pour in the chicken broth and water, then add the chopped broccoli, salt, black pepper, and dried thyme. Stir to combine.
Bring the mixture to a boil, then reduce heat to medium-low and cover the pan.
Simmer for 10-12 minutes, stirring occasionally, until the orzo is tender and most of the liquid is absorbed.
Return the cooked chicken to the pan and stir to combine.
Remove the pan from heat and stir in the shredded cheddar cheese until melted and creamy.
Serve immediately while hot.