Heat the butter over med-high heat in a saucepan with a tight fitting lid. Once it's melted, add the onion and cook until soft. Then add the garlic and cook another minutes, until fragrant.

Stir in the orzo and toast it, stirring pretty often, until it browns a little bit. Then pour in the broth and milk. Bring it up to a boil. Once it's boiling, stir it and put the lid on. Lower the heat the med-low.

Cook for 10-15 minutes, until the liquid has mostly absorbed and the orzo is soft. Stir it once or twice while it Cooks. Once its done, remove it from the heat, stir in the cheese until melted and season to taste.