HAHA That's what I'm making tomorrow night, probably won't be as fancy as yours though.
I saw on Masterchef a contestant making a roux and she put onion into it at the start, have you ever tried that? I really want to try it, but that fucking white sauces is so annoying to make because you constantly have to be stirring it and I'm afraid I'll fuck it up and have to start again.
		
		
	 
LOL
Lasagne weather, just gave my sister a batch since she has broken her wrist.
And @inigo your post reminded me of learning to make white sauces years ago, I was such a nervous cook back then - I just couldn't get past the first stage.
IE the butter/flour bit panicked me, and I kept putting that bit through sieves to get the lumps out, or chucking it in a blender.
So I gave up for a few years.
Now
Once you get the roux thing going, butter/flour, mixing in the milk is actually a breeze.
I always make it when I have five other things going, so I can just come back now and again.
I have discovered - you make the lumpy butter/flour mess, add some of the milk and leave  it to warm around the lumpy mess, come back mix it to smooth, and it's easy - the warmed milk makes it easier.
Just keep repeating, until it's the consistency you want. 
Or buy one of those things that cost thousands and stir for you.
Haven't tried the onion thing that way- but we do creamy onion in white sauce with corned beef. Add onion poached in the microwave to white sauce.