Heat olive oil in a large pot over medium heat.
Add the diced chicken, season with salt and pepper, and cook until browned and cooked through, about 5-7 minutes.
Stir in minced garlic and cook for an additional minute until fragrant.
Pour in chicken broth and bring to a simmer.
Add the orzo and broccoli florets to the pot, stir well, and let it cook for 10-12 minutes.
Reduce heat and stir in the whole milk and shredded cheddar cheese until melted and creamy.
Taste and adjust the seasoning with more salt or pepper if needed.
Serve warm, garnished with additional cheese if desired.