- Preheat oven to 350F. Coat 9-inch square baking pan with cooking spray.
- In medium bowl, combine cocoa, dates and coffee.
- Add boiling water and stir until cocoa has dissolved.
- Let stand until completely cool, about 10 minutes.
- Meanwhile, spread walnuts in shallow baking pan and bake until lightly toasted and fragrant, 4 to 6 minutes.
- Set aside to cool. Keep oven on.
- In food processor, combine flour, baking powder, salt and toasted walnuts; process until walnuts are ground.
- Transfer mixture to large bowl and set aside.
- With rubber spatula, scrape cooled cocoa mixture into food processor.
- Add egg, egg white, 1 cup Sugar, oil and vanilla and process until smooth, stopping once or twice to scrape down sides of work bowl. Add to reserved flour mixture and stir just until dry ingredients are moistened.
- Pour batter into prepared baking pan, spreading evenly.
- Sprinkle with remaining 1 tablespoon Sugar.
- Bake until brownies are firm around edges and just set in center, 25 to 30 minutes.
- Transfer pan to wire rack and cool completely.
- To serve, coat sharp knife with cooking spray and cut into 16 squares.