The repeat is between the red lines. I did nine repeats on the original, but feel free to do as many as suits your tastes.
Yarn: roughly 70-75g of worsted weight yarn in two contrasting colors.
Needles: size 7, or whichever size is comfortable and produces a solid fabric. I find double-knittng works up a bit more loosely for me than 'plain' knitting, hence going down a needle size.
Cast on 50 stitches with both yarns held together. I used long tail, but you can use any cast-on method you prefer.
Begin every row by slipping the first stitch of both colors together purlwise with yarn in front, and knit the last stitch of every row (again, both colors) with both yarns held together.
One row is a pass along one side of the blanket. Odd rows will feature MC as the background color, even rows will feature CC as the background.
The chart begins and ends with two plain rows on either end; don't leave those out, it keeps the edges from looking cramped!
Follow the chart from the bottom up, repeating the section marked off by red as many times as you wish. I did nine repeats, and it made a blanket that fit on one couch cushion just so.
Once your blanket is long enough, and you've knit the end of the chart (don't forget the two plain rows!) loosely bind off all stitches with both yarns held together. Weave in ends, block if you like (or not, cats don't really care) and enjoy!