Probably one of the easiest to follow Cathedral Window tutorials I've ever read. Seriously need to try this.
How to make 3D Faux Cathedral Window Quilt Blocks -- I did this forever ago, maybe with my daughter when she was young. Easy and fancier than it is hard!
Church Round Windows
Cathedral window ornament tute
Diary of a Quilt Maven: Faux Cathedral Windows Pincushion Tutorial--no hand sewing for this method!
Instructions for a cathedral window cushion, but the illustrations are good, so for a quilt, just keep going.
cathedral windows tutorial via kerri horsley
cathedral window quilt - Google Search
Quilting : Pinwheel Surprise Folded Cathedral Style quilt block
Cathedral Window Quilt Blocks - I like the way these are arranged in groups off four around the negative space.