Line bottom and sides of 9" square baking pan with nonstick foil. Preheat oven to 350*.
In a glass bowl, microwave chocolate and butter on high 2 minutes, until melted. Whisk smooth.
Add espresso powder and whick until smooth.
Stir in sugar, eggs, coffee liqueur, baking powder and salt.
Whisk in flour and pecans.
Spead batter in pan. Bake 22 minutes. Cool on rack.
Melt white chocolate and place in small food storage baggie. Seal bag; snip off tiny hole. Drizzle brownies with white chocolate. Refrigerate 10 minutes to set chocolate.