Working diagonally across the design area, stitch a series of stepped horizontal stitches, each over two threads.

Working back up the diagonal line, fill each space between the horizontal stitches with a vertical stitch.

Repeat the process down and back up the diagonal line to complete each box.

Start the next parallel diagonal row six threads apart from the last row and complete the design area to be filled.

Work across the design area from the opposite direction. Stitch a small square in between each existing line to create a new diagonal line at a right angle.  Where the lines cross, fill the already completed square with a cross stitch.