It looks like the same pattern as the signature blocks I made in a swap awhile back. Those started out with a 4-1/2" square, with 2-1/2" squares diagonally sewn on two corners to make triangles. But it could easily be enlarged to use 5-1/2" squares with 3" (check my math - I just woke up!) squares to make the triangles.
Then just turn each square opposite the one beside it as they're sewn together.
I'll see if I can find the pattern. BRB!
Edit: Here you go. Just make them 5-1/2 unfinished", and reverse the lights/darks, and there's your quilt!
http://www.quilterscache.com/I/IndianHatchetBlock.html