Oh! This thread is in Bygones, no wonder I couldn't find it again as I was looking in Foodtalk!
Here's my shortbread recipe, but it's based on US ingredients, so you probably should add 1/4 cup of flour to each cup in the recipe. Plus it has sugar, so maybe not as historically accurate as it should be, but it is very good!
Medieval Shortbread
3 cups all purpose flour (so add another 3/4 cups to this)
1/2 cup caster sugar
2 tsps cinnamon
1/2 tsp powdered cardamon
1/2 tsp powdered ginger
3/4 tsp allspice
1/2 tsp salt
1 cup butter at room temperature
1. Preheat oven to 350 F.
2. Combine sugar, spices, and salt evenly.
3. On strong, clean, kneading surface mix gently, by hand, the spice mix into the flour.
4. Squeeze butter in hands, and bit by bit add spiced flour by working it into butter on the board. Take time to thoroughly integrate dry ingredients and butter mixture.
5. Press batter into 8" square, shallow pan.
6. Score the surface of the batter to make "fingers" (2" by 1") of shortbread. Also make several shallow fork pricks on each "finger".
8. Bake 1 hour or less until firm and yellow--not brown.
9. Cool in pan--break into shortbread fingers and serve. Often tasting better several days old, keeps beautifully if stored in an airtight tin or wrapped tightly in foil.
