Saute the chopped onion in a medium pot with butter for 4-5 minutes, or until it starts to brown.
Add the garlic and mushrooms and cook for 7-10 more minutes, until the mushrooms begin to brown.
Now, add the wine and cook until it almost completely evaporates.
At this point, add the orzo, broth, milk, salt, and pepper and simmer everything together. Stir occasionally and let it cook for about 10 minutes, until almost all of the liquid is gone. Taste, add more seasonings if needed, and serve.
