Heat the olive oil in a large skillet over medium heat. Season the chicken breast with half the salt and half the pepper.
Cook the chicken until browned on both sides and the internal temperature reaches 165°F (74°C), about 6-8 minutes per side depending on thickness. Transfer to a plate and set aside.
Substituting for orzo. Ditalini, small shells, or elbow macaroni swap in 1:1 with no other changes — same size, same starch release, same liquid ratio. Acini di pepe or pastina also work but cook in about 5 minutes and release more starch, so use ¾ cup and drop the broth to 2½ cups (600 ml). Israeli (pearl) couscous holds its shape well but thickens less; add an extra ½ tsp arrowroot. Avoid Moroccan couscous, which turns to mush, and quinoa, which fights the flavor. General rule: any small pasta under a 10 minute package time drops straight in.
Rice instead of pasta. Long-grain white rice works but retimes the dish — 1 cup rice needs about 2 cups (480 ml) broth and 18-20 minutes covered, so add the carrots later to keep them from going to mush.
Stir often. Orzo sinks and scorches. Scrape the bottom of the pan every couple of minutes while it simmers.
Chicken thighs. Boneless skinless thighs work in place of breast and stay juicier; cook to 175°F (80°C) for the best texture.
Thicker or thinner. The sauce tightens as it sits. Loosen with a splash of broth, or simmer an extra minute or two to thicken.
Wine substitute. Swap in an equal amount of broth plus 1 tsp lemon juice for the same brightness.