The formula though, spoke to me of larger fatter loaves, my back of the envelope modified take on it was;
50% white wheat flour, 48% Spelt flour of light extraction, 2%rye flour (in culture), 2 % salt, 2% butter,1% fresh yeast.
I mixed the flour& water 3 min , (dough temp. 28c) let it rest 30 min. added the remainder of things mixed 10 min. in a slow gentle gear.
After 60 min, did a stretch&fold, tossed in a plastic box and put it outside in the woodshed over night, 8C.
In the morning, i let it warm up for an hour, scaled 600gram loaves, rounded them firmly, after 30 min., shaped and placed on a shifted bed of flour for the final proof, which turned out to be only 30 min.
The crust action was pronounced, good flavour,(but not great, have to work on that). I think the butter would have been better reduced to 1%. Inside, the crumb was inconsistent, some of it looked plenty wild , like Swiss Emmental cheese.
It was an interesting batch, gives me modification ideas for later.