I had seen a number of these blocks on various sites, and found this awesome tutorial by 'Blue Elephant Stitches' on 'Moda Bake Shop' that uses a jelly roll.
I wanted an extra colour on my granny square so needed to do the maths. This block is the result of me checking that I'd done the calculations right. The only thing I need to change is to make the top right and bottom left squares slightly longer - instead of 3" I'll go for 3.5". This will enable me to cut a block to be 12" square - or more if I used a scant 1/4" seam rather than the slightly over 1/4" seam I was using.
The fabric is this block is 'Bake Sale' by Lori Holt, with Kona snow. I have a jelly roll of 1930's reproduction fabric that would look lovely made up in this block - and if my maths is still correct I could cut out 24 blocks from it.
I think this block will turn into a mini wall hanging but may have a short-term role as a dolly quilt for my daughter K.
I'm linking up to 'WIP Wednesday' at 'Freshly Pieced' and then I'll do some browsing of other blogs! :-)