Rich Espresso and Cream Cheese Brownies (Bon Appetit)

Why I Love This Recipe
Ingredients You'll Need
1/2 c butter
3 oz unsweetened chocolate, finely chopped
2 oz bittersweet or ss chocolate, chopped
3/4 c a-p flour
1/4 t baking powder
1/4 t salt
3 L eggs
1 L egg, separated
1 1/4 c brown sugar
1/3 c chopped toasted walnuts
3 1/2 t instant espresso powder
1 T coffee liqueur
12 oz cream cheese, room temp
1 c powdered sugar
Directions
Melt butter in heavy med saucepan over low heat. Add unsweetened and bittersweet chocolates; stir until melted. Cool, stirring occasionally.
Grease 9x13 baking pan. Combine sifted flour, baking powder, and salt in small bowl. Using electric mixer, beat 2 eggs, 1 egg yolk, and brown sugar in L bowl until very thick, about 4 minutes. Fold in chocolate mix, then flour mix.
Transfer 1/3 c batter to small bowl and reserve for topping. Fold walnuts into remaining batter. Spread batter with nuts evenly in prepared pan. Refrigerate until firm, about 15 minutes.
Position rack in center of oven and preheat to 325. Combine espresso powder and liqueur in small bowl and stir until powder is dissolved. Blend cream chz and powdered sugar in processor until very smooth, stopping occasionally to scrape down bowl. Blend in espresso mix, remaining egg, and egg white.
Spread crm chz mix over chilled batter in pan. Transfer reserved 1/3 c batter to pastry bag. Carefully pipe batter in paprallel lines down length of pan, spacing 3/4" apart. Draw toothpick through straight lines to make chevron design. Bake about 33 minutes, then cool in pan on rack.
Cover and refrigerate brownie until well chilled. Serve cold.