Prepare cake mix as directed, except substitute egg whites for eggs and butter for oil. Bake in a 9x13 inch pan as directed. Pour pineapple over cake as soon as it comes out of the oven. Cool.
Meanwhile, in another saucepan, combine cornstarch and remaining water; add raspberries. Bring to a boil over medium heat; boil and stir for 2 minutes or until thickened. Remove from the heat; stir in lemon and pineapple juice. Cover and chill for 30 minutes.
To make the frosting: Prepare instant pudding as directed. Add lemon juice and fold in whipped topping. Let sit 10 minutes. Spread over cake and top with raspberry sauce. Garnish with almonds if desired.