Woven Basket stitch Also known as Diagonal Basketweave stitch. It is not difficult, just a bit time consuming but well worth it. Very impressive!

Woven Basket stitch also known as Diagonal Basketweave stitch (similar Criss-cross stitch)
Cast on an even number of stitches.
Row 1 - wrong side: Slip 1, * purl the second stitch on the needle and leave on needle, purl the first stitch, slide both stitches off the needle; rep from * to last stitch, slip 1.
Row 2 - right side: * Skip 1 stitch and  insert needle from back to front between lst and 2nd stitches and knit into the front 2nd stitch, leave on needle, then knit the skipped stitch, slide both stitches off the needle; rep from * to end.
Repeat Rows 1 - 2.