This is one piece dressing at it's best:
My first thought for a pattern was this:
This is the Love Notions Melody Dolman pdf pattern. The collar is different which I think I would prefer, the pattern would need to be lengthened, and converted to a pull over. All are doable. If you already have this pattern, all you need to do is locate some linen or a linen blend.
Obviously if you already have a similar pattern, use it. Save those dollars for fabric or notions.
Happy Stitching!