Cheese Sauce - Not incredibly healthy - Be warned!!!

This is my Fiance Mailies favorite dish, and one that I learnt how to make as a kid (when I was not as health concious) - That being said it is made with organic butter and healthy pasta and that sort of thing, but its definetely not healthy down the right side (see my previous post about left side right side health)
Recipie for the sauce. - This makes ALOT
1/2 Cup Butter
1/2 Cup Flower
3 - 4 Cups Milk (depends on how thick you want the sauce to be)
500 Grams Cheddar Cheese (i prefer old, mailie prefers mild)
Pinch of salt
1-2 Bottles of Organic Spagetti Sauce (whichever you like)(depends on how ROSEA you want your sauce)
I usually end up freezing half of the cheese sauce and only mixing in 1 can of spagetti sauce - still makes TONS of sauce - enough for 8 people.

The beginning is the only slightly tricky part.
Melt the butter in a medium saucepan, be sure not to get it very hot.
Then slowly mix in the flower, adding maybe a tablespoon at a time and making sure its blended in well. Keep the heat VERY low as to now cook this mixture - This is called a Rue and makes the base to alot of sauces - get good at making a rue and you can become a master sauce maker.
Next mix in the milk. very slowly and turning the heat up slightly maybe to a 2 or 3 setting on your stove out of 10... so still very low.
Cut the cheese in easy melting slices - stir into the sauce and heat it up (do not turn up the heat! - you cant cook the sauce or it goes chunky) Stir very often, almost constantly until the cheese has melted in. - Again be sure to keep the temperature LOW
Mix in the spagetti sauce and some salt. Mix well.
If the sauce seems chunky it could be that you had the head too high, it could be taht the cheese you used was crap... in any case there is a solution - Throw the whole sauce mixture into a blender and blend on high for 30 seconds.
Thats it.
Cook chicken or sea food and some pasta and voila.
Easy and best in my opinion is sea food. Cook the pasta with the frozen sea food medly and strain together. Once the pasta is 2 minutes out from being done, put the frozen medly in, as soon as it starts to boil again its done - Strain and serve.