I got delayed on this post when I realized that I had no idea what a #medieval #baker used in place of #bakingPowder. It turns out it's "#hartshorn", which is actually the horns of male red deer, dried at high heat and then ground down to a powder.

The ammonia that's part of the active ingredient wafts away during the cooking, making your #kitchen smell terrible. For the few #baking products that still require the airy #leavening it produced, modern bakers use something called #BakersAmmonia.

Last bit in this thread for completeness - cooked 15 mins in 425 ⁰F convection oven (i.e., with fan on)
Go 450 if no fan
Also added about ¼ tsp #BakingPowder (not soda) to the flour before the "buttemilk"

This works and is flaky as there are bits of butter throughout that melt and rise as it cooks.
Enjoy with some jam or honey (or both)!