1. Preheat the oven to 375 degrees F. Put the almonds and sugar in a food processor and blend until the consistency of flour, about 45 seconds. Pour in the egg whites and mix until the dough is smooth and loose, about 30 seconds.
2. Line an 8-by-11-inch cookie sheet or pan with parchment. Spread the batter with a wet spatula to evenly cover the pan in a thin layer. Bake until the batter sets and is golden brown, rotating the pan once about halfway through baking, about 18 minutes.
3. While still warm, cut the dough into 12 to 14 rectangular biscuits or other desired shape. (A pizza wheel makes cutting very easy.) Transfer to a cooling rack.
4. Meanwhile, put the chocolate in a clean microwave-safe bowl. Heat the chocolate at half power, stirring at 30-second intervals until melted, about 2 minutes. Drizzle the chocolate over the biscuits. Cool completely. Serve. Store in an airtight container.