1. Cut two perfect squares of flannel: one 42x42 inch and one 36x36 inch.
2. Mark the center of each side of the blanket and pin the two centers right sides together. This means that the large square will hang off the edges of the small square. You are lining them up in the middle, not the corners.
3. Starting at the center of each side, sew to the edge of the smaller piece of fabric, leaving the larger fabric puff on the corner alone.
Step 4: Fold the blanket together so that the outside edges are flush. Line up that edge on your cutting mat, and draw a 90 degree line from the stitch stopping point. This line helps you know where to fold in the next step.
Step 5: Fold the corner down, keeping the bottom edges flush and crease the fabric.
Step 6: Draw a line where the crease was. Sew down that line. Clip off excess fabric. Repeat on all four corners and turn blanket right side out. Even if you are anti-ironing, you HAVE to iron this baby down before sewing if you want it to look nice. I used a zig zag stitch to go around where the two fabrics meet, which also closed off the hole.