🎂 Root Beer Float Layer Cake Recipe

piece of root beer float cake in foreground with remainder of cake in background

5 from 9 votes

🎂 Root Beer Float Layer Cake Recipe

This root beer float cake recipe tastes just like a root beer float, but even better because it's a cake! And it's the ultimate happy birthday cake. Layers of chocolate cake, flavored with root beer extract, then painted in root beer syrup, making it super moist, with a light, fluffy, and not too sweet shortening (Crisco) based icing. The root beer cake is topped with marshmallow fluff to look like melted ice cream, with a cherry on top! If you are looking for summer cakes or a birthday cake recipes, this is your cake!

Course Dessert

Cuisine North American

Keyword cake, root beer, root beer float

Special Diet Vegetarian

Prep Time 35

Cook Time 30

assembly, frosting and decorating 1

Total Time 2 5

Servings servings

Calories 758kcal

Author Terri Gilson

Equipment

Ingredients

Cake:

2 cups sugar
1 ¾ cup all purpose flour
¾ cup unsweetened cocoa powder
1 ½ teaspoon baking powder
1 ½ teaspoon baking soda
¾ teaspoon salt
1 cup milk
½ cup canola oil
2 large eggs
2 tablespoon root beer extract *I used 2 bottles of Lorann's concentrated root beer extract
1 cup boiling water
1 cup root beer soda

WHIPPED CREAM BUTTERCREAM FROSTING

Part 1:

1 lb. powdered sugar (sifted)
2 ½ cups shortening * I use Crisco or Tenderflake

Part 2:

¾ cup white granulated sugar
½ teaspoon salt
3 tablespoon meringue powder
½ cup (less 2 tbsp) boiling water
1-2 teaspoon Brown gel colouring I use Wilton icing coloring- you may need more, depending on what brand you use
1 tablespoon root beer extract *I used 1 bottle of Lorann's concentrated root beer extract (pictured in ingredients section)

Garnish:

1 maraschino cherry
2-3 tablespoon marshmallow fluff/marshmallow creme
1-3 tablespoon chocolate sprinkles add as many as you desire

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Instructions

Preheat oven to 350 degrees F/175 degrees C. Prepare (I use Wilton Cake release https://amzn.to/3mh24FK -affiliate link) three 8 inch cake pans and set aside.
In the bowl of a stand mixer (with paddle attachment), combine flour, white granulated sugar, cocoa powder, baking powder, baking soda, and salt
2 cups sugar, 1 ¾ cup all purpose flour, ¾ cup unsweetened cocoa powder, 1 ½ teaspoon baking powder, 1 ½ teaspoon baking soda, ¾ teaspoon salt
Add eggs, milk, oil and root beer extract to the flour mixture. Beat on medium speed for 2 minutes.
1 cup milk, ½ cup canola oil, 2 large eggs, 2 tablespoon root beer extract
Slowly stir in boiling water and continue mixing for another minute or until combined.
1 cup boiling water
Pour cake batter evenly into 3- 8 inch prepared cake pans until each cake pan is ⅔ full. **Batter will be runny
Bake cake for about 30 minutes or until cake tester comes out clean and/or the tops of the cakes spring back when lightly touched. Let cakes cool for 10 minutes before removing from pans to finish cooling onto a wire rack
While cakes cool, boil root beer in a heavy sauce pan until reduced by half. It will form a syrupy liquid. Brush warm cakes with this root beer concentrate and let finish cooling.
Once cool, cover in plastic wrap and refrigerate for several hours or overnight. **this is not critical, but you do get the best results if you do this
1 cup root beer soda

Whipped Cream Buttercream:

Part 1:

Put shortening in the bowl of a stand mixer and gradually add powdered sugar. Beat about 5 minutes until mixture is very creamy and fluffy. Set this aside.
2 ½ cups shortening, 1 lb. powdered sugar (sifted)

Part 2:

In a very clean large bowl mix dry ingredients (sugar salt and meringue powder). Add BOILING water and immediately mix on high speed.
¾ cup white granulated sugar, ½ teaspoon salt, 3 tablespoon meringue powder, ½ cup (less 2 tbsp) boiling water
Beat until stiff peaks form, about 8 minutes. When mixture begins to get stiff add root beer extract.
1 tablespoon root beer extract
Combine both mixtures and beat together for another 8 minutes. The frosting will be very light and creamy. Add brown food coloring if you desire. Cover. DO NOT REFRIGERATE.
1-2 teaspoon Brown gel colouring
The frosting may be kept at room temperature for 1 month. Whip with a spoon each time you use it to restore fluffiness. * Makes enough to ice this 3 layer 8 inch cake

Assembly & Garnish:

Transfer cakes to a cake plate. Fill and frost the cake layers then run a comb along the sides of the cake. (see sample method in video). Pipe a border with a #21 icing tip (optional).
Add the marshmallow fluff, then a maraschino cherry in the centre and sprinkle with chocolate sprinkles.
1 maraschino cherry, 2-3 tablespoon marshmallow fluff/marshmallow creme, 1-3 tablespoon chocolate sprinkles
For the ULTIMATE root beer float experience, I recommend servign this cake with vanilla ice cream

Notes

Expert Recipe Tips:

Use room temperature ingredients. Bringing your eggs and milk to room temperature helps them incorporate more easily into the batter, resulting in a smoother, more even-textured cake.
Choose the right root beer. Avoid using diet root beer or brands with strong wintergreen or licorice notes, as they can give the cake an off-putting flavor. A classic, well-balanced root beer works best (e.g., A&W or Barq's).
Don’t skip the syrup step. Brushing the layers with root beer syrup not only boosts flavor but also adds critical moisture. If you’re short on time, you can make the syrup while the cakes bake to save a few minutes.
Make ahead for best flavor. Allowing the cake to chill overnight after brushing with syrup gives the flavors time to develop and helps the cake firm up for easier frosting and slicing.
Whip the frosting well. To get the ultra-fluffy texture in the whipped buttercream, be sure to beat each part thoroughly, especially the meringue powder and sugar mixture—this is where the structure comes from.
Fix a runny frosting. If your frosting is too soft or runny, beat in a bit more powdered sugar or chill it for 15 minutes. Avoid adding more shortening unless necessary, as it can make it greasy.
Crumb coat for a smooth finish. Apply a thin layer of frosting first to catch crumbs, chill for 15–30 minutes, then add your final coat. This gives you a cleaner, more polished result.
Don’t refrigerate the frosting. This frosting is stable at room temperature and actually performs best unrefrigerated. Refrigerating it can make it hard and dull the fluffiness.
Decorate just before serving (optional). If using marshmallow fluff for the “melted ice cream” effect, apply it closer to serving time for the best visual appeal, as it may slowly slide or absorb into the frosting over time.

Videos:

Combing a cake: Combing a cake is a very simple decorating technique, and it works very well on this root beer cake. If you've never done it, then check out this video: How to ice and comb a cake *skip the refrigeration part, as this whipped buttercream should NOT be refrigerated!

Making a Border: A shell border is what you'll typically see used on cakes, using a #21 tip. I make a loose shell border. If you are not sure how to do a shell border, then check out this video: How to make a shell border with a #21 tip (it's the 3rd one)

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