Root Beer Float Cake (or Cupcakes)

There are some desserts that never go out of style. The root beer float is one of them — that simple pairing of fizzy root beer poured over creamy vanilla ice cream still has the power to make you feel like a kid sitting at a diner counter. The foam, the sweetness, the way the ice cream melts into the soda — it’s nostalgic and comforting in a way that’s hard to top.

But here’s the thing: floats melt fast. As fun as they are, they don’t travel well, they don’t last, and they’re not exactly practical to serve to a big crowd. That’s where Root Beer Float Cake comes in. It takes everything you love about the classic float — the sweetness, the vanilla, the spice — and bakes it into a dessert that holds its own at birthdays, cookouts, or weeknight cravings.

This isn’t just vanilla cake with soda poured in. The batter is built with root beer reduction for concentrated flavor, cocoa for depth (think of the way cola and chocolate complement each other), and buttermilk for tenderness. The frosting carries its own root beer twist too, lightened with plenty of vanilla to echo that “float” flavor. The result? A cake that tastes like the childhood classic, but polished enough to serve to grown-ups.

You can bake it as a sheet cake for easy slicing, round layers for a more formal look, or cupcakes if you want grab-and-go servings. However you shape it, the flavor will be the same: a dessert that’s sweet, nostalgic, and completely addictive.

Yield: 1 (9×13) cake or 2 round layers, or 12–18 cupcakes.

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Root Beer Float Cake (or Cupcakes)

Quick recipe summary: A tender, moist cake made with real root beer in the batter, topped with a creamy vanilla-root beer frosting. It tastes like the classic float in dessert form — fun, nostalgic, and crowd-pleasing.

Ingredients

For the Cake:

• 1 ½ cups root beer (not diet)
• ½ cup unsweetened cocoa powder
• ½ cup unsalted butter, cubed
• 1 cup granulated sugar
• ½ cup brown sugar, packed
• 2 large eggs, room temperature
• 1 teaspoon vanilla extract
• ½ cup buttermilk
• 2 cups all-purpose flour
• 1 ½ teaspoons baking soda
• ½ teaspoon salt

For the Frosting:

• ½ cup unsalted butter, softened
• 3 cups powdered sugar
• ¼ cup root beer reduction (simmer 1 cup root beer down to ¼ cup)
• 1 teaspoon vanilla extract
• Pinch of salt
• 2–3 tablespoons heavy cream or milk, as needed for texture

Instructions

1. Prepare root beer reduction: Pour 1 ½ cups root beer into a small saucepan and simmer over medium heat until reduced to ¾ cup. Reserve ½ cup for the cake and set aside ¼ cup for the frosting. Let cool.
2. Make the cake base: Preheat oven to 350°F (175°C). Grease and flour a 9×13-inch pan, two 8-inch round pans, or line cupcake tins with liners.
3. Combine wet ingredients: In a large saucepan, melt butter with cocoa powder and ½ cup of the reduced root beer, whisking until smooth. Remove from heat and stir in both sugars until dissolved. Let cool slightly.
4. Add eggs and dairy: Whisk in eggs, vanilla, and buttermilk until well blended.
5. Mix dry ingredients: In a separate bowl, sift together flour, baking soda, and salt. Gradually add dry mixture to wet, stirring until just combined (do not overmix).
6. Bake: Pour batter into prepared pan(s). Bake 30–35 minutes for 9×13 cake, 25–28 minutes for round layers, or 18–22 minutes for cupcakes, until a toothpick inserted comes out clean. Cool completely before frosting.
7. Prepare frosting: Beat butter until light and fluffy. Gradually add powdered sugar, alternating with root beer reduction and heavy cream, beating until smooth and spreadable. Beat in vanilla and salt.
8. Frost and serve: Spread frosting generously over cooled cake or pipe onto cupcakes. Garnish with maraschino cherries for the full “float” effect, if desired.

Notes & Tips

• Root Beer Choice: Use a brand with strong vanilla and spice notes (Barq’s, A&W, or Mug work well). Avoid diet — the flavor and sweetness won’t hold up.
• Texture: The cocoa deepens the flavor and keeps the cake from being overly sweet. Don’t skip it.
• Frosting Tip: If the frosting is too loose, add more powdered sugar. Too stiff? Add a splash of cream.
• Serving Suggestion: Top each cupcake with a small scoop of vanilla ice cream for a playful presentation.
• Storage: Keep frosted cake covered at room temperature up to 2 days, or refrigerate up to 5 days. Unfrosted cake layers can be frozen up to 2 months.
• Cooling Rack: A sturdy wire cooling rack helps cakes and cupcakes cool evenly before frosting (I recommend this one from Amazon).
• Piping Bags: For cupcakes, disposable piping bags with a star tip make it easy to get that soda-fountain swirl (these are my go-to set on Amazon).

There’s something about Root Beer Float Cake that feels both retro and fresh at the same time. It taps into that nostalgic soda-fountain vibe, but in a form that’s practical for real life. You can bring it to a potluck, serve it at a birthday party, or just bake it on a Sunday afternoon and have dessert sorted for the week.

The root beer flavor is distinct but not overpowering — it’s balanced with cocoa and vanilla so every bite tastes like the float you remember. And the frosting? That’s what really seals it, creamy and light with just enough root beer tang to keep you coming back for another forkful.

If you’ve ever loved a float, you owe it to yourself to try this cake. It’s more than dessert — it’s nostalgia you can slice.