hi tan,
google white sauce recipe and you will get an easy microwave whitesauce recipe on the taste website. best tip when making white sauce, is if it goes lumpy, whisk it and lumps will disappear! add a bit of cheese for a nice cheesy flavour.
your daughter must be like mine - my DDis 5 and her favourite meal is "cream sauce noodles" - it is very boring really, just pasta and whitesauce and some diced vegies. she loves it.