The recipe yield is:
"Once you have tried homemade Zwieback, you will never again think of it as only a "baby cracker." The seductive aroma from baking this fragrant cracker will envelop your kitchen. The final result is a complexity of flavor that is nothing less than spectacular. Zwieback takes a lot of effort to make -- but it's worth every minute. The method for making Zwieback is quite different from that for most other crackers. "Zwieback" means "twice baked." First you bake a yeast bread, aromatically flavored with nutmeg, cinnamon, vanilla, and mace. Then you slice it and slowly dry the slices in a slow oven. For convenience, make the bread over a two-day period. Bake the bread the first day and dry it the second. If stored in an airtight container, Zwieback will keep almost indefinitely. In a small bowl, combine the yeast with 1/2 teaspoon of the sugar and the warm water. Set aside in a warm place until the mixture starts to foam, about 5 to 10 minutes. In a small saucepan, mix the milk and the remaining 1/4 cup of the sugar. Add the 4 Tablespoons butter and heat until the butter has completely melted. Transfer the mixture to a bowl and allow to cool to lukewarm. In a large bowl or in the food processor, combine the cooled milk mixture with the yeast mixture. Stir in the vanilla. Add the mace, cinnamon, and nutmeg and mix well. Beat in the egg. Slowly add the flour, adding just enough to make a smooth dough that is not sticky. If mixing by hand, the dough will become too stiff to stir, and you should knead in the last of the flour with your fingers. Then knead well for at least 5 minutes, forming the dough into a ball. If using a food processor, pulse until the dough comes together in a ball. Place the dough in a large, lightly oiled bowl and turn it over to coat all sides. Cover with a damp towel and set the dough in a warm place until it has doubled in bulk, about 1-1/2 to 2 hours. Punch the dough down and knead a few strokes. Cover and allow the dough to double in size again, 30 to 45 minutes. Punch the dough down and turn it out onto a lightly floured surface or pastry cloth. Knead about 30 seconds to remove the air. Divide the dough into 3 equal portions. With your hands, roll each into a smooth cylinder or loaf about 2 inches thick and 9 inches long. Place the loaves crosswise on a lightly greased or parchment-lined baking sheet, leaving at least 3 inches between the loaves. Brush all exposed surfaces of each loaf with the melted butter. Set the baking sheet in a warm place and let the loaves rise until doubled in bulk, about 30 minutes. Preheat the oven to 375~F. Bake the risen loaves for 25 to 30 minutes, or until the bottoms are reddish brown and make a hollow sound when thumped. Allow the loaves to cool thoroughly on racks. Preheat the oven to 200~F. Cut the cooled loaves into 1/2-inch slices. Place the slices flat on the baking sheet and allow them to dry out in the oven for 45 to 60 minutes, or until thoroughly dry. Check occasionally and turn the slices over as they dry on one side. When dry, raise the oven temperature to 300~F. for 10 to 20 minutes to brown the Zwieback slightly. Cool on a rack. Yield: 40-50.