I switched to this approach recently, both for nutrition and so I didn’t have to wait for the kettle to boil.
The recipe suggests a 1.5 to 1 ratio for steel cut oats, but my experience was 1:1 or you’ll have excess water in the bottom (after leaving it for 12 hours). The ratio might have to do with the container – I use hermetic/airtight ones, so it could be that water isn’t evaporating.
After a couple of weeks, I started adding things (just before eating, to not throw off the water ratio) like:
There’s a link at the bottom of the recipe for 19 variations.