These can be made with or without the espresso powder.
⅔ c. sugar
2 tbsp. vegetable oil
1 large egg
1 large egg white
1 oz. unsweetened chocolate, melted and cooled
1 tbsp. instant espresso powder (optional)
2 tsp. vanilla
1 c. flour
¼ c. cocoa powder
1 tsp. baking powder
¼ tsp. salt
½ c. powdered sugar
Add sugar and oil to a medium bowl. Beat on medium until combined. Add the egg and egg white and beat until light and lemon colored. Blend in melted chocolate, espresso powder (if used), and vanilla. Set aside.
In another bowl, sift together the flour, cocoa, baking powder and salt. Gradually add to the chocolate mixture, blending on low until just combined. Divide south in half and scrape onto two pieces of waxed paper (dough will be soft). Wrap completely and freeze for at least 2 hours or overnight.
Preheat oven to 350°. Line two baking sheets with parchment paper and set aside. Place powdered sugar in a wide container. Working with one batch of south at a time, pinch off several bits (about six at once to work quickly), roll into 1-inch balls, and drop into the powdered sugar. Shake vigorously to completely coat the balls (no dough should show through). Transfer to prepared baking sheets. Bake for about 7 minutes until they are cracked on top but still soft in the center.