BillsBonBon made those, but there are a few different ways to do attic windows. You can do the traditional methid with the Y seams, uise half square triangles in the corners, or place a square over the strip, face down, sew on the diagonal, and cut off the remainder. I think one os ShellyQ's tutorials on beginner blocks may show that method.
When machine piecing, sometimes I leave more than the 1/4 from the Y, and go back in with thread and needle.