This cake is pure, unadulterated joy. It’s the one I requested every single year as a kid, and now I make it for my own kids. It’s not about being sophisticated; it’s about that classic, soft, vanilla-buttermilk crumb and the colorful confetti sprinkles that make everyone smile. The secret? Clear vanilla extract. It gives you that iconic “birthday cake” flavor and keeps the crumb a beautiful, bright white.
Quick Look
| Prep | Cook | Total | Feeds | Level |
|---|---|---|---|---|
| 30 min | 30 min | 2+ hours | 12 | A joyful project |
Grab These
- For the cake:
- 2 ½ cups all-purpose flour
- 1 ½ cups granulated sugar
- 1 tbsp baking powder
- ½ tsp salt
- ¾ cup unsalted butter, softened
- 3 large egg whites, room temp
- 1 tsp clear vanilla extract
- 1 cup buttermilk, room temp
- ½ cup rainbow jimmies (not nonpareils!)
- For the frosting:
- 1 cup unsalted butter, softened
- 4 cups powdered sugar
- 2 tbsp heavy cream
- 1 tsp clear vanilla extract
- Pinch of salt
Let’s Make It
Preheat your oven to 350°F (175°C). Grease and flour two 8-inch round cake pans. I even line the bottoms with parchment paper—it’s foolproof.
In a large bowl, whisk together the flour, sugar, baking powder, and salt. Add the softened butter, egg whites, vanilla, and half the buttermilk. Beat with an electric mixer on medium for 2 minutes, then scrape down the bowl.
Add the remaining buttermilk and beat for another minute. The batter should be pale and fluffy. Now, gently fold in the rainbow jimmies with a spatula. Overmixing will turn your batter a strange color.
Divide the batter evenly between the pans and bake for 25-30 minutes, until a toothpick comes out clean. Let them cool in the pans for 10 minutes, then turn out onto a wire rack to cool completely.
For the frosting, beat the butter until it’s light and pale. Gradually add the powdered sugar, then the cream, vanilla, and salt. Whip it for 3-4 minutes until it’s incredibly light and fluffy.
My Two Cents
- Calories: A celebratory 450 per slice
- Storage: Stays moist at room temperature under a cake dome for 3 days.
- Swaps: No buttermilk? Add 1 tbsp of lemon juice or vinegar to 1 cup of milk and let it sit for 5 minutes.
- Pro-Tip:* Use “jimmies” (the long, cylindrical sprinkles) instead of “nonpareils” (the little balls). The jimmies won’t bleed their color into the batter as much.
You Asked, I’m Answering
Q: Why clear vanilla?
A: It gives that classic “birthday party” flavor and keeps the cake white, allowing the sprinkles to really pop. If you only have regular vanilla, it will still taste great but will have a tan color.
Q: My cake layers domed in the middle!
A: To get flat layers, try using cake strips! You soak them in water and wrap them around the outside of the pan. It works like a charm.