Preheat oven to 350°F. Spray 8-inch square baking pan with nonstick spray.

Combine flour, baking powder, and salt in small zip-close plastic bag. Seal bag and shake until mixed well. Whisk together egg, egg white, liqueur, and vanilla in large bowl. Add sugar, butter, and hot water; whisk until blended well. Whisk in cocoa and espresso powder. Add flour mixture, stirring just until blended; stir in walnuts. Scrape batter into prepared pan and spread evenly.

Bake until toothpick inserted into center of brownies comes out with a few moist crumbs clinging, about 20 minutes. (Do not overbake.) Let cool completely in pan on wirerack. Cut into 16 squares.

1 square: 111 Cal., 5g total fat, 15g Carb, 1g fiber, 3g protein

FYI: Brownies can be cakey or fudgy. Ours are somewhere in between. If you like, you can bake them for a few minutes less to make them more fudgy or a few minutes more to make them more cakey.