I saw a book for knitting kimonos at my local library. I can't think of the name of it now. But they had you just knitting rectangles and piecing them together. This is a simple shape. Here is a baby sweater pattern that has similar construction. The only difference would be to make two back pieces instead of the back and two front pieces for the cardigan. Scroll down to the bottom and you'll see how this would be constructed. You could knit the sleeves separately as a flat piece, sew the shoulder seams, sew the sleeves to the body, then seam this from the bottom of the sleeve to the top and down the sides. You could also sew the shoulder and side seams, then pick up stitches and knit the sleeves in the round. The type of neckline on this would be called a boat neck, if you sew.