Pat chicken breast cubes completely dry with paper towels. Season evenly with garlic powder, onion powder, 1/2 tsp salt, and black pepper.
Heat olive oil and 1 tablespoon of butter in a large deep skillet or Dutch oven over medium-high heat. Add seasoned chicken in a single layer and sear undisturbed for 3 to 4 minutes until golden-brown crust forms. Flip and cook for another 2 minutes until cooked through. Transfer chicken and juices to a clean plate and set aside.
Reduce heat to medium. Melt the remaining 2 tablespoons of butter in the same pan, scraping up flavorful browned bits from the bottom. Add minced garlic and dry orzo pasta. Toast the orzo grains for 1 to 2 minutes, stirring constantly until fragrant and lightly golden.
Pour in chicken broth, Italian seasoning, and remaining 1/2 tsp salt, stirring thoroughly. Bring to a gentle boil, then reduce heat to low, cover with a lid, and simmer for 7 to 8 minutes until orzo is almost al dente, stirring occasionally to prevent sticking.
Uncover and stir in heavy cream, bite-sized broccoli florets, and the cooked chicken along with any resting juices. Simmer uncovered for 3 to 4 minutes, stirring gently until broccoli is tender-crisp and bright green.
Remove skillet from heat. Stir in freshly grated Parmigiano-Reggiano cheese until completely melted into a velvety, creamy sauce. Season with additional salt and black pepper to taste.
Garnish generously with extra grated parmesan, freshly cracked black pepper, and chopped flat-leaf parsley. Serve warm directly from the skillet.