In a large bowl beat butter with an electric mixer on medium to high speed for 30 seconds. Add brown sugar, espresso powder, and baking soda; beat until combined, scraping side of bowl occasionally. Add egg whites, yogurt, and almond extract; beat until combined. Beat in cocoa powder. Beat in as much of the flour as you can with the mixer. Using a wooden spoon, stir in any remaining flour. If necessary, cover and chill dough for 1 to 2 hours or until easy to handle.