Gather ingredients. Roughly chop the broccoli florets.
Cut the chicken breast tenderloins into bite-size pieces. (You can totally use chicken thighs or whole breasts for this recipe. I just saw these tenderloins at the grocery store and the price was right!).
Transfer the chicken to a medium mixing bowl with 1 tsp salt, black pepper, garlic powder, onion powder, and smoked paprika. Toss until evenly coated.
Melt butter and olive oil in a large broiler pan or an oven-safe sauté pan over medium heat. Add seasoned chicken.
Cook until the chicken is cooked through, about 6 minutes per side, 12-15 minutes total.
Next, add the orzo to the pan and toss it with the chicken to lightly toast it, about 2 minutes.
Deglaze the pan with the chicken broth. Stir everything together and turn the heat down to medium-low.
Shred cheddar cheese and set aside. Set oven to broil on high.
Add room temperature whole milk to the skillet and stir to combine.
Add chopped broccoli florets. Simmer everything for about 8 minutes or until the orzo is done to your liking, and most of the liquid has been absorbed.
Stir in half of the cheddar cheese.
Add the rest of the cheddar cheese on top and sprinkle with the remaining salt and any extra pepper you might like.
Transfer to oven and broil for 3-5 minutes until the cheese has melted, or just put the lid on your pan and melt the cheese on the stovetop.
*I used chicken breast tenderloins because I found them for a great price, but boneless, skinless chicken breasts or thighs also work. Cut them into bite-sized pieces (about 1 inch) and cook until the thickest pieces reach 165°F. Or to save time, use about 3 cups of chopped or shredded cooked chicken and add it when you stir in the cheese.**We use Better Than Bouillon to keep our broth costs low.***I use frozen broccoli because it’s inexpensive and easy to keep on hand. Run it under cold water to thaw slightly, then chop any large florets. Fresh broccoli also works, but it'll have a little more bite. I like frozen broccoli here because it’s blanched before freezing so it becomes perfectly tender in the casserole.****Mild cheddar gives a gentler flavor, while sharp cheddar adds a stronger cheesy punch (which I love). Use whichever cheddar you prefer. Shred it from a block for the smoothest melt.