I saw this recipe on Tablespoon.com and thought it sounded like a fun idea. Their plan for the frosting made me gag however, so I've completely changed that. I made this cake for a family birthday party and it was a great hit.
For the best flavor you'll need to purchase either root beer concentrate or root beer flavored syrup. The concentrate can be found in the baking aisle with the spices and extracts. The syrup is usually with ice cream condiments like hot fudge and sprinkles. Here's a photo of both:
They are worth getting because you can either make homemade root beer with the concentrate or put the root beer syrup on vanilla ice cream. Yum!
The root beer flavor will come through more if you refrigerate the cake overnight. As for the garnish, save that for just before serving. The crushed candies will melt after about an hour or two and the syrup will kind of do the same.
ROOT BEER FLOAT CAKE
adapted from Tablespoon.com
1 box white cake mix with pudding
3 egg whites
1/4 cup vegetable oil
1 (12 oz) can (1 1/2 cups) root beer
2 tsp. root beer concentrate (or 2 Tbsp. root beer flavored syrup)
1 (3.4 oz) package instant vanilla pudding mix
1 cup milk
1/2 tsp. vanilla
1 (8 oz) container Cool Whip, thawed
garnish: crushed root beer barrels or root beer flavored syrup
Preheat oven to 350 degrees. Lightly spray bottom only of 9x13 baking dish with cooking spray. In a large bowl, beat cake mix, egg whites, vegetable oil, root beer, and root beer concentrate or syrup on low speed for 30 seconds. Beat at medium speed for 2 minutes, scraping bowl occasionally. Pour into pan. Bake for 28-32 minutes or until toothpick inserted in center comes out clean. Cool completely; about 1 hour.
(Optional: for best root beer flavor, after cooling, cover cake with plastic wrap and refrigerate overnight.)
In a large bowl, whisk together pudding mix, milk, and vanilla for 2 minutes. Fold in Cool Whip and spread over cooled cake. Garnish with crushed root beer barrels or syrup just before serving. Keep refrigerated.