Beat whipping cream and brown sugar in chilled large bowl until stiff. Fold in walnuts. Spread small amount of whipped cream mixture on each of 3 crackers. Arrange crackers, frosted sides down and with edges touching to form a rectangle, on serving plate. Spread rectangle with about quarter cup whipped cream mixture. Layer with 3 crackers. Repeat layers 9 times. Gently press torte together. Carefully turn torte on its side with spatula so crackers are vertical. Frost sides and top with remaining whipped cream mixture. Refrigerate at least 6 hours (torte will mellow and become moist). 10 SERVINGS; 305 CALORIES PER SERVING.