Heat oven to 350°F. Grease bottom only of 13x9-inch pan. In large bowl, combine all brownie ingredients; beat 50 strokes with spoon. Spread in greased pan. Bake at 350°F. for 28 minutes. Remove from oven.
Meanwhile, in small bowl, beat 1/4 cup butter and brown sugar until light and fluffy. Add 1 egg, 2 teaspoons coffee granules and 1 teaspoon vanilla; blend well. In medium bowl, combine walnuts and chopped chocolate. Add brown sugar mixture; blend well.
Spoon and carefully spread filling over baked brownies. Return to oven; continue to bake an additional 17 to 20 minutes or until light brown.
In small saucepan, melt chocolate chips and 1 tablespoon butter over low heat, stirring constantly until smooth. Remove from heat. With wire whisk, stir in 1/8 teaspoon coffee granules and enough milk for desired drizzling consistency. Drizzle over warm brownies. Cool 45 minutes or until completely cooled. Cut into bars.