Heat butter or olive oil in a large deep skillet or Dutch oven over medium-high heat. Add the diced chicken and sprinkle with lemon pepper seasoning. Sauté for 5-7 minutes, stirring occasionally, until the chicken is golden brown and cooked through to 165°F. Remove chicken to a plate and set aside.

If the pan looks dry, add a bit more oil. Add the chopped onion and minced garlic, stirring frequently for 2-3 minutes until they soften and become fragrant. Avoid browning the garlic.

Add the dry orzo to the pan and stir constantly for 1-2 minutes until the pasta turns slightly golden and smells nutty. This toasting step enhances the flavor.

Pour in the chicken broth and lemon juice, scraping the bottom of the pan with a wooden spoon to release the browned bits. Bring to a boil, then reduce heat to medium-low for a gentle simmer.

After about 5 minutes of simmering, stir in the broccoli florets. Cover with a lid and continue cooking for 5-8 minutes until the orzo is tender and has absorbed most of the liquid, and the broccoli is crisp-tender.

Return the cooked chicken to the pan along with the lemon zest and grated Parmesan cheese. Stir until the cheese melts into the sauce. If the mixture is too thick, add a splash of broth or water to loosen it.

Season with salt and black pepper to taste. Garnish with fresh chopped parsley and serve hot.