Dice onion, garlic, chicken, and broccoli before starting. Set out all other ingredients (cooking goes quickly).
Heat olive oil in a large nonstick pot over high heat. Add onion and cook for 2 minutes. Stir in garlic and cook for 30 seconds. Add chicken, season with salt and pepper, and cook for about 5 minutes or until mostly cooked through. Add frozen vegetables (no need to thaw) and broccoli. Stir for 2–3 minutes until thawed and the broccoli is crisp-tender. Transfer mixture to a plate and cover with foil to keep warm.
In the same pot, melt butter over medium heat. Sprinkle flour on top and whisk constantly for 1 minute. Gradually whisk in chicken stock, then add milk and uncooked orzo. Stir in Italian seasoning.
Bring to a simmer, then lower heat until it's gently bubbling. Cook uncovered for 7 minutes, stirring often to prevent sticking. The mixture will still be a bit soupy at this stage (it will continue to thicken after adding veggies and Parm).
Return chicken and veggies to the pot and stir through. Add 3/4 cup Parmesan (a handful at a time), stirring in between additions, until melted. Taste and season with more salt and pepper to taste.
The consistency should be creamy and similar to risotto. Add a splash of milk if you want it thinner. Serve hot, topped with remaining Parmesan and fresh parsley. Enjoy while hot.
Video
Notes
Note 1: Avoid powdery, sand-like Parmesan; it doesn’t melt right and will be too salty. I grab a block of Parmesan and grate it with a microplane or the small holes of a box grater for the best texture! Gently pack in the measuring cup.Storage: Store leftovers in an airtight container in the fridge for up to 3 days. Reheat on the stove over low heat, adding a splash of milk for more creaminess.