1. Beat egg whites until stiff, but not dry. Mix sugar with coffee and salt; gradually beat into egg whites.
2. Cover cooky sheet with aluminum foil; mark off a 9-inch circle on foil. Spread meringue within circle, building up the edge to about 2 inches.
3. Bake in slow oven (275°) 1 1/2 to 2 hours, or until crisp and dry. Remove from oven; cool. Carefully peel away foil; place meringue on serving plate.
4. Fill shell with ice cream; drizzle with the mocha sauce. Sprinkle with chopped walnuts. Cut in wedges to serve; spoon more sauce over each serving.