1. HEAT oven to 350 degrees F. Lightly spray large cookie sheet with no-stick cooking spray.
2. PLACE cake mix in large bowl. Melt shortening in microwave-safe bowl in microwave on HIGH (100% power) for 30 seconds. Stir until smooth. Add melted shortening, eggs and water to cake mix. Stir with wooden spoon until evenly moistened. Batter will be stiff. Spray hands with no-stick cooking spray. Work dough with hands until cake mix is totally absorbed.
3. DIVIDE dough in half. Shape each half into a 9 x 3-inch loaf on prepared cookie sheet.
4. BAKE 25 minutes. Remove from oven. Cool on cookie sheet 15 minutes. Cut each loaf into 3/4-inch slices. Stand upright on cookie sheet.
5. BAKE an additional 15 minutes. Remove from oven. Cool 10 minutes.
6. PLACE each frosting in a separate quart-size resealable food storage bag. Close. Microwave on HIGH 8 seconds or just until soft. Knead gently in bag. Press frosting to one corner of bag. Cut a very small opening off the corner. Drizzle each frosting over cooled biscotti to make stripes.