Get two pounds of white breadcrumb and bake it a second time. Grind it in a mortar and put it through a sieve so it becomes like flour. For every pound of that sieved substance, add as much again of fine flour, two and a half pounds of finely sieved sugar and four ounces of leaven ground in a mortar and moistened with fifteen fresh eggs; then everything should be mixed together three-quarters of an ounce of raw anise ground into powder and four ounces of rosewater. When everything is thoroughly mixed and beaten together so that it looks like fritter batter, let it sit for two hours in a warm place. Beat it again, adding in four more eggs and an ounce of salt; then let it sit for another hour. Than have a buttered tourte pan and put the filling into it so it is a finger's width in depth. Put that into an oven that is not too hot. Leave it there until it is dry. Remove it and with a sharp knife cut it into little long rectangles, as wide or as narrow as you like. Just as soon as they have been cut up, put them immediately into marzipan tourte pans, set out apart with paper under them, and put them back into the oven with a very moderate heat. Leave them there for half an hour, turning them several times until they have firmed up.
1/4 lb plain breadcrumbs
1/4 lb white flour
10 oz sugar
1 oz yeast
1 tsp rosewater
1.5 tsp anise seeds, ground
Beat the eggs, and beat the yeast into them. Add the rosewater. Mix the dry ingredients together, then gradually beat the wet ingredients into them. Leave covered for three hours, then turn out into a buttered baking pan and cook for 40 minutes at 250 degrees, or until the surface has a slightly springy texture when tested.
Let cool for 5 minutes to reduce stickiness, then cut into approximately 1' x 5' "fingers". Place in a baking dish lined with parchment paper, and bake for twenty minutes at 350 degrees, or until solidified.
Serve with a dish of snow, preferably.
These have a much softer and chewier texture than modern biscotti, though they retain the twice-cooked aspect. As Scappi's instructions are ambiguous, he may mean to produce something as rock-hard as the modern version, but given that the second baking is only supposed to take half an hour at a moderate heat, this seemed unlikely to me.
I also overlooked the step of adding additional eggs in the middle of the resting period, which did not seem to do the biscotti any harm. It is possible that a higher egg-content would make them somewhat firmer, though again it seems unlikely that they would reach the stiffness of modern biscotti.