1. Preheat oven to 350°.
2. To prepare cake, coat a 12-cup Bundt pan with cooking spray; dust pan with 1 tablespoon flour.
3. Place granulated sugar and next 3 ingredients in a large bowl, and beat with a mixer at medium speed until well blended (about 5 minutes). Add eggs and egg whites, 1 at a time, beating well after each addition. Beat in 1 teaspoon vanilla.
4. Weigh or lightly spoon 11.25 ounces flour (about 2 1/2 cups) into dry measuring cups; level with a knife. Combine flour and next 5 ingredients in a medium bowl, stirring with a whisk.
5. Add flour mixture and buttermilk alternately to sugar mixture, beginning and ending with flour mixture. Stir in zucchini and chocolate chips. Pour batter into prepared pan. Bake at 350° for 1 hour or until a long wooden pick inserted in cake comes out clean. Cool pan on a wire rack 10 minutes. Remove cake from pan; cool completely on wire rack.
6. To prepare glaze, combine 3/4 cup powdered sugar and 3 tablespoons cocoa in a small bowl; stir with a whisk. Combine milk, 2 tablespoons chocolate chips, and 1/2 teaspoon vanilla in a 1-cup glass measure. Microwave at HIGH 30 seconds or until chocolate melts. Combine powdered sugar mixture with chocolate mixture, stirring with a whisk. Drizzle glaze over cake.
Young Chefs can:
Measure shredded zucchini and chocolate chips
Add zucchini and chocolate chips to batter
Older Chefs can:
Help shred zucchini
Prepare glaze, and drizzle over cake