Line 2-quart bowl with plastic wrap; lightly oil.

Place egg yolks and 1/2 cup whipping cream in small bowl; beat slightly with fork. Sprinkle gelatin over egg yolk mixture. Let stand without stirring 5 minutes to soften.

Melt chocolate chips in top of double boiler over hot, not boiling, water. Stir about 1/2 cup melted chocolate into egg yolk mixture. Stir egg yolk mixture back into remaining chocolate in top of double boiler. Continue to heat until gelatin is completely dissolved.

Beat egg whites and salt in clean large bowl with electric mixer at high speed until foamy. Gradually beat in sugar until stiff peaks form. (After beaters are lifted from egg white mixture, stiff peaks should remain on top, and when bowl is tilted, mixture will not slide around.) Fold chocolate mixture into egg white mixture with rubber spatula.

Beat whipping cream until soft peaks form; fold into chocolate mixture. Pour into prepared bowl. Cover and refrigerate 4 hours.

Prepare Chocolate Cake and White Chocolate Cut-Outs.

Place cake on serving plate. Unmold mousse onto cake. Remove plastic wrap. Trim edge of cake around mousse, if necessary.

Place white chocolate baking bar in small resealable freezer bag. Microwave on MEDIUM (50%) 2 minutes. Turn bag over; microwave on MEDIUM 2 to 3 minutes or until chocolate is melted. Knead bag until chocolate is smooth. Cut off very tiny corner of bag; drizzle chocolate over mousse. Refrigerate until white chocolate is set, about 30 minutes. Garnish, if desired.

Preheat oven to 375°F. Grease bottom and sides of 9-inch round baking pan. Add 2 to 3 teaspoons flour to pan. Gently tap side of pan to evenly coat bottom and sides with flour.

Combine sugar and shortening in large bowl. Beat with electric mixer at medium speed until light and fluffy, scraping down side of bowl once. Add eggs, water and vanilla; beat well.

Combine flour, cocoa, baking soda, baking powder and salt in small bowl. Add to shortening mixture; beat with electric mixer at medium speed until smooth. Pour batter into prepared pan.

Bake 20 to 25 minutes or until cake tester or toothpick inserted into center comes out clean. Cool 10 minutes in pan.

Loosen edge and remove to wire rack; cool completely.

Melt chocolate in small bowl set in bowl of very hot water, stirring occasionally. This will take about 10 minutes.

Pour onto waxed-paper lined cookie sheet. Refrigerate until firm, about 15 minutes.

Cut out large triangle shapes with sharp knife.

Immediately lift shapes carefully from waxed paper with spatula or knife. Refrigerate until ready to use.