Heat oven to 325 degrees. Place almonds in the bowl of a food processor, add 1 tablespoon of sugar to absorb the oil generated by the nuts, and grind until medium fine.
Place egg whites in the clean bowl of an electric mixer. Beat on high speed, using the whisk attachment, until egg whites are stiff. Add the remaining sugar slowly; continue beating until egg whites are very thick, 2 to 3 minutes.
Beat in cocoa until combined. Fold in almonds, and mix until completely blended.The batter should be quite thick and sticky.
Line two baking sheets with Silpats (French nonstick baking mats) or parchment paper. Dampen hands, and shape about 1 heaping teaspoonful of dough into a 1-inch ball. Pinch the ball with your fingers to form a teardrop shape, and place on baking sheet. Continue process, spacing cookies about 2 inches apart, until all the dough is used.
Bake until cookies are slightly cracked and soft but slightly firm, 12 to 14 minutes. Let cool on sheet for several minutes, then transfer to a rack to cool completely.
Place chocolate in a mixing bowl. Heat heavy cream in a small saucepan over medium heat until simmering. Pour over chocolate, and let stand; stir until all the chocolate has melted and mixture is smooth. Let cool until thick yet pipeable. The ganache should be the consistency of toothpaste. Fill a pastry bag fitted with a #11 round pastry tip with the ganache. Pipe about 1/2 teaspoon of chocolate onto the flat side of a cooled cookie, and place another cookie on top. Press together gently so chocolate oozes out slightly. Return cookie to rack, and let chocolate harden. Repeat process with remaining cookies.