Cute quilt! Depending on how big your squares are in the blocks and your batting, which should tell you how close to quilt, I might just do diagonal lines either between your "knots" or right down through the middle of them. If your batting requires closer quilting you could do both. Stitch in the Ditch is always an option but is not quick. Another option might be long rectangles in the white space - but that might not be quick either. I am sure that others will weigh in. Can't wait to see what you do.