Preheat oven to 350F (180C). Line two baking sheets with parchment paper. Cut half of the chocolate in smaller chunks. Set aside until ready to use.

Melt the other half of the chocolate over bain-marie and set aside to cool slightly.

Meanwhile, whisk together 1 cup of powdered sugar, cocoa powder, cornstarch and salt into a medium bowl.

Using a mixer start whipping the egg whites until they begin to rise and hold their shape.  While whipping, gradually beat in 1/2 cup powdered sugar until stiff and firm, about 2 minutes.

Using low speed of your mixer, gradually add the dry ingredients mixture over the whipped whites. Add melted chocolate, chocolate chunks and almond extract. Stir to combine.

Place 1/2 cup powdered sugar into a bowl. Using your ice cream scoop take equal portions of dough and roll into the sugar, coating thickly. Place on the prepared baking sheet. Repeat with remaining dough, keeping 2 inches space between cookies.

Bake for 10 minutes until cracked. Cool on sheets on rack for 10 minutes. Transfer to rack and cool.