Here is one of the oldest recipes I could find:
3 egg whites
6-7 cups Confectioner’s sugar, plus more to coat the board
Preheat oven to 375° F.
Line baking sheets with parchment paper.
In a food processor, grate the chocolate. Add the egg whites. Add 3-4 cups of the sugar. The mixture will thicken up. When it gets too stiff for the processor blade, turn the dough out into a bowl. Add as much additional sugar as needed to make a dough that is not sticky. Using confectioner’s sugar, coat a rolling pin and board. Roll the dough and cut with cookie cutters. Place on the cookie sheets, leaving about ½ inch between each biscuit. Bake for 10-12 minutes. They will rise up and puff while baking.
Yield: 80 2” biscuits