Preheat oven to 350° F.
Spray 9x13-inch pan with nonstick cooking spray.
Combine cake mix, BOOST® Vanilla and eggs in a large mixing bowl. Beat with electric mixer on medium speed for 2 minutes. Stir in mandarin oranges and ½ cup pineapple.
Pour batter into pan and sprinkle with almonds.
Bake 35-40 minutes or until toothpick inserted in center comes out clean. Cool for 15 minutes.
Combine powdered sugar and 2 tablespoons of the reserved pineapple juice in a small bowl; mix until smooth. Spread over warm cake.
Cool completely before serving.
Garnish each serving of cake with whipped topping, if desired.