Heat the milk in a saucepan until just about to boil (do not let it boil).

At the same time, in another saucepan, heat the butter (over medium-low) heat until melted. Add the flour and stir until smooth. Cook until the mixture turns a light, golden color.

Add a pinch of nutmeg and salt to the butter/flour mixture. Remove from the heat to stir.

When the milk is hot (not boiled!), add the butter/flour mixture and stir until it becomes creamy. If it has lumps, add a little bit of (hot) milk and stir. If it is too liquid, add a little bit of flour (only a pinch at the time!). Do not allow the sauce to boil.