I haven't tried this yet, but a recent request on Nextdoor prompted a search, which yielded two recipes.
One recipe is from The SF Chronicle - cut and pasted below, and another is a re-creation from the "Sweet" book, which follows at the bottom of this post.
Reading the article, I found out the original creator of the cake was a man called Ernest Weil, who wrote a book that included the original recipe. This led to the discovery of several new copies of Mr. Weil's book, each at the cost of $300+ and a website that offers a downloadable pdf version for a $25.00 donation to any of the non-profits listed on their website.
https://www.seriouseats.com/blums-coffee-crunch-cake
