This recipe comes from the German translation of Time-Life's “Die Küche in Italien”, originally published in 1968, as part of their recipe for cannelloni. The horrible US cups and spoons measurements drive me mad, and in any case, they're completely wrong in this case. The quantities given here are appropriate for the cannelloni or lasagne recipes, and about 5 times as much as the book recommends for the former.

quantity		ingredient	Step
50 g		Butter	1
50 g		Plain flour	2
1 litre		Milk and cream	3
5 g		Salt	3
		Pepper (optionally; could be white pepper)	3

The total quantity of milk and cream should be 1 litre. Depending on taste, you can make it all milk or up to 50% cream; I don't think that the sauce would benefit from more than 50% cream. Let me know if you try this anyway. I personally use 800 ml milk and 200 ml cream.

Procedure

Start at least 20 minutes before using in another recipe.

1. Melt the butter in a saucepan, taking care not to let it get hot.
2. Add the flour and stir until uniform.
3. Add milk and cream, salt (and pepper if desired). Heat and bring to the boil, stirring constantly with an electric whisk.