Not done quite this but I’ve done the following which both worked:
1. Created a topsoil by placing leaves down in autumn and then sowing a quick mustard cover crop in March (fully harvested by late April) – the soil was totally ready to receive onion clumps (sown in modules in late March) or 6 -8 seeds direct and I harvested a fine crop.
So you can definitely create good soil using a leaf mulch and grow a successful crop in spring.
2. Hilling up potatoes using a combination of comfrey leaves, grass clippings and rotted horse manure.
I have been creating good soil in each of my 4 beds one year at a time by growing potatoes traditionally (i.e. creating a trench, filling it with manure ,comfrey leaves and BFB) and then hilling up as described.
I now have two of my four beds with great aerated soil and loads of worms after growing potatoes this way in 2014 and 2015. In 2014, I also overlaid horse manure at the end of October and simply left to rot on the surface. No digging was done, but obviously when creating the trenches, a certain mixing of topsoil with deeper stuff took place.
I think this method will probably work, although the question is what yield you get.
Funnily enough, I’ve laid down leaf mulch on two beds not growing potatoes in 2016 – we’ll see what happens. One is for parsnips, onions and carrots. The other is for beans of a variety of kinds.
We’ll see how they get on.