In a large pot, melt the butter and saute the minced garlic for about 30-60 seconds.
Add the orzo, milk, water, and salt and stir together, then bring to a simmer. Cover and simmer for about 7 minutes, stirring once or twice to break the orzo apart.
Add the Parmesan cheese and stir well, then add the spinach and cook just until wilted, about 1-2 minutes.
If it looks a little dry, add a splash of milk to make it creamy, then top with black pepper, red pepper flakes, and more Parmesan cheese. Serve!
Notes
This recipe makes 4 small-ish servings of pasta. Stir in some cooked white beans or chicken to bulk it up a little if desired. :) You can use frozen spinach also, but you MUST thaw it first. I've found that tossing freezer-cold spinach into the mix makes the sauce kind of seize up and have a less-creamy-more-grainy texture. It's not the absolute worst thing, but it's not my favorite either.