I’m looking for a pattern for a one piece hat and scarf for my 3 year old for this coming winter.
Something like this?
I haven’t seen a pattern, but there must be one out there… or you could improvise by picking up stitches on a hat on each side.
Lion Brand has a pattern called “Little Red Riding Hood’s Hooded Scarf” if that is the type of pattern you’re looking for…
http://cache.lionbrand.com/patterns/BK4K-0701008.html?noImages=0
The pattern is free, but you have to register to use it (which doesn’t take too long). Hope that helps 
Here’s one for purchase.