completely. In a small bowl, dissolve drink mix and instant coffee in hot water. Add powdered sugar, Bit's of Brickle and margarine; beat until fluffy. Slice cooled cake into 4 layers; gently spread 1/3 filling between each layer. Frosting: In small bowl, combine Cool Whip and powdered sugar. Frost top and sides of cake. Garnish cake with whole or halves walnuts. Refrigerate cake for at least 2 1:41 PM hours.