For cake: Preheat oven to 325 degrees F. Grease bottoms of 12-inch, 9-inch and 4-inch round pans and line them with parchment or wax paper. Sift together flour and baking powder. Set aside. Cream together butter and sugar until fluffy. Set aside. Beat egg whites until stiff, but not dry. Set aside.
With mixer at low speed, alternately add flour and milk to butter. Beat in vanilla. Gently fold in egg whites and pour into prepared pans. Bake until toothpick inserted into center comes out clean.
For mousse: Melt white chocolate in double boiler or very carefully in microwave. Cool. Whip cream until soft peaks form. On low speed, pour in cooled, melted white chocolate.
For buttercream: Cream together shortening and butter. Add vanilla. Gradually add sugar 1 cup at a time, beating well on medium speed. Scrape sides often. Add milk and beat at medium speed.
To assemble: Spread raspberries over both the 12-inch and 9-inch layers of prepared cake. Top each with raspberries, approximately 1/2-inches apart. Place 9-inch cake layer on top of 12-inch layer. Place 4-inch layer on very top. Decorate with buttercream.
The recipes for this program, which were provided by contributors and guests who may not be professional chefs, have not been tested in the Food Network's kitchens. Therefore, the Food Network cannot attest to the accuracy of any of the recipes.