Preheat the oven to 325°F. Get out a jelly roll pan or baking sheet; no need to grease it. Grease a pan-sized piece of parchment; or tear off a sheet of non-stick aluminum foil., Whisk together the flour, salt, and baking soda. Set the mixture aside., In a medium-sized bowl, whisk the egg whites until frothy., Add the sugar, cocoa powder, espresso powder, oil, and vanilla, beating until smooth., Whisk in the milk powder, then the flour mixture., Stir in 1/2 cup of the chocolate chips., Place the parchment or foil on your work surface. Spread the batter on the parchment or foil, using a spatula or dough scraper to spread it as thin as possible., Lift the paper or foil onto the baking sheet. Sprinkle the remaining chips atop the batter., Bake the brittle for 20 minutes. Remove it from the oven, and cut it into squares using a knife, bench knife, or rolling pizza wheel; don't separate the pieces., Return the pan to the oven, and bake the brittle for an additional 5 minutes. Remove it from the oven, and cool on the pan., When the brittle is cool, break it into pieces. Store airtight at room temperature.