It is a variation of the 10 minute block as clem55 and Janie W stated. Go to YouTube and type in 10 minute block! I made a 12 block quilt this week-end at retreat and was tickled to death at how easy and fast it was. Because the edges of the "set in" square are on the bias it's easy peasy to curve the edge and stitch down. I think I'll use my fairy frost for this idea. Would be so cute done with 5" charm squares too.