This is not a complicated block to make but at 6" finished the center square finishes at 4" which makes a strange size to cut for the center on-point square so I used a combination of techniques once again to make my block.
I paper pieced the small triangle corner sections and used the stitch and flip method to sew them to the center square like shown. The upper left corner shows how to line up the corner with the block to sew your 1/4" seam and the lower right corner shows the corner after stitching, flipping and ironing it in place.
With the center section done, just add sashing and cornerstones. The sashing strips are cut 1 1/2" wide by 4 1/2" long and the corner squares are cut as 1 1/2" squares. Here's how the parts go together. Just sew the rows together and you are done! You can download the paper pieced corners here. The pattern includes a template for the center if you prefer to add the corners to an on point center instead of using the method I describe above.
I wonder how Nancy Cabot would have set this block. On point makes the most sense to me.