Instructions

1. 1
   In a saucepan, melt the butter over medium-low heat. Whisk in the flour to make a roux.
2. 2
   Cook the roux over gentle heat for 3–5 minutes, but do not brown. This cooking is necessary to remove the floury taste.
3. 3
   In a separate pot, begin heating the milk. Peel the onion, but do not cut it.
4. 4
   Add the onion and bay leaf into the pot with the milk. Keep stirring until milk is heated to 80°C. Do not let the milk adhere and cook to pot bottom.
5. 5
   Remove onion and bay leaf.
6. 6
   Gradually whisk the heated milk into cooked roux. Add salt and pepper to taste.
7. 7
   Stir and cook for 15 minutes until thickened. No lumps should be present.