New to crossed trebles? We have a tutorial for you here:
http://thecrochetproject.com/blog/how-to-crochet-crossed-stitches

While we are normally fans of top down garments, this bottom-up circular- yoked sweater is worked with the ultimate comfort in mind. It is slouchy and stretchy, with simple detailing at the neck. Perfect for wearing brambling, apple picking and less active pursuits.

Sizes
XS(S, M, L, 1X, 2X, 3X, 4X, 5X)

Finished Chest Circumference
88 (97, 108, 117, 128, 136, 147, 156, 168) cm/ 34.5(38, 42.5, 46, 50.5, 53.5, 58, 61.5, 66) in

Materials
7 (8, 9, 10, 10, 11, 11, 12, 13) 50g balls Blacker Yarns Gotland 4ply, 100% Gotland wool, 175m/190yds/50g) in Grey
3mm (US C or D) hook
4mm (US G) hook
5 Removable stitch markers

Tension
18 sts and 19 rows in seed stitch (see special stitches) to 10 cm/4 in using 4.0 mm hook (or size needed to achieve tension)

Difficulty Rating
Intermediate

Skills Needed
Basic crochet stitches, crossed stitches, working in rows, working in rounds with turning, working into row ends, working in back loop only.

Construction
Bottom up, seamless yoked sweater.