In a small skillet heat oil over medium heat; add in onion and saute for about 10 minutes or until lightly browned; add in the garlic and chili flakes the last 2 minutes of cooking (the onions must be lightly browned!).
In a heavy-bottomed saucepan whisk/stir together milk, chicken broth, flour and black pepper over low heat until smooth, thickened and heated though.
Add the the onion/garlic mixture to the prepared sauce; mix until heated through.
Add/mix in Parmesan cheese and season with salt if desired.