Small-batch dark chocolate birthday snack cake finished with cloud-like chocolate American buttercream and colorful birthday sprinkles.
This small-batch chocolate cake is perfect for intimate celebrations, quick weeknight treats, or any time you want a simple, impressive dessert. The recipe is a one-bowl batter and yields a rich, dark chocolate cake topped with a fluffy American-style chocolate buttercream. It’s easy, reliable, and quickly became a favorite at home.
I first made this for Griffin’s 2nd birthday and it disappeared faster than I could photograph it, so I baked it again — happily, no complaints. Here’s how to make it.
How to Make Dark Chocolate Birthday Snack Cake
Bake the Cake
Preheat the oven to 350°F. Line a 9×9-inch baking pan with parchment paper, leaving an overhang so you can lift the cake out after it cools. Lightly grease the pan if you prefer. In a large bowl, whisk together the flour, granulated sugar, dark cocoa powder, baking soda, baking powder, and salt.
Stir in the buttermilk and vegetable oil until combined. Add the whole egg, egg yolk, and vanilla extract and whisk again. While whisking, slowly stream in the hot coffee (or hot water/decaf if preferred). The coffee boosts the chocolate flavor but can be omitted if necessary. Mix until the batter is smooth and no dry spots remain.
Pour the batter into the prepared pan and bake for 28–30 minutes, or until a toothpick inserted in the center comes out mostly clean with a few moist crumbs. Allow the cake to cool completely in the pan, then lift it out using the parchment overhang.
Make the Chocolate Frosting
In the bowl of a stand mixer fitted with the paddle attachment (or using a hand mixer), beat the room-temperature unsalted butter for 5–7 minutes until light and silky, scraping down the bowl as needed. Add the salt and vanilla and mix briefly to combine.
Add the powdered sugar in two-cup increments, mixing for about 3 minutes after each addition until incorporated. Add the cocoa powder and mix until uniform, scraping the bowl as needed. Add heavy cream one tablespoon at a time until you reach a soft, spreadable consistency — about 3 tablespoons gives a very fluffy buttercream. Beat an additional 1–2 minutes to fully incorporate the cream and aerate the frosting.
Spread the frosting over the cooled cake with an offset spatula for an even layer. Use the back of a spoon or the spatula to create decorative swirls, then finish with rainbow sprinkles. Serve and enjoy.
Dark Chocolate Birthday Snack Cake
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- Author: Elizabeth Buuck
- Prep Time: 15 min
- Cook Time: 30 min
- Total Time: 45 minutes
- Yield: 16 small slices or 9 large slices
Description
Rich dark chocolate cake topped with fluffy chocolate American buttercream and rainbow sprinkles.
Ingredients
For the Dark Chocolate Cake
- 1 1/2 cups all-purpose flour
- 1 cup granulated sugar
- 1/4 cup + 2 tablespoons dark cocoa powder
- 1 tsp baking soda
- 1/2 tsp baking powder
- 1/2 tsp salt
- 1/2 cup buttermilk, at room temperature
- 1/4 cup vegetable oil
- 1 large egg + 1 egg yolk, at room temperature
- 2 tsp pure vanilla extract
- 1/2 cup hot coffee
For the Chocolate American Buttercream
- 3/4 cup unsalted butter, at room temperature (1 1/2 sticks)
- 1/2 tsp salt
- 1 tsp pure vanilla extract
- 4 cups powdered sugar
- 1/2 cup cocoa powder
- 2–4 tbsp heavy cream, at room temperature
Instructions
For the Dark Chocolate Cake
- Preheat the oven to 350°F and line a 9×9-inch pan with parchment.
- In a large bowl, whisk together the flour, sugar, cocoa powder, baking soda, baking powder, and salt.
- Whisk in the buttermilk and oil.
- Whisk in the egg, egg yolk, and vanilla.
- While whisking, slowly pour in the hot coffee and mix until smooth with no flour lumps.
- Pour the batter into the prepared pan and bake at 350°F for 28–30 minutes. Let cool completely.
For the Chocolate American Buttercream
- Beat the butter in a stand mixer with the paddle attachment for 5–7 minutes, scraping the bowl as needed.
- Add the salt and vanilla and mix to combine.
- Add the powdered sugar in 2-cup increments, mixing about 3 minutes after each addition.
- Add the cocoa powder and mix until evenly combined, scraping the bowl as needed.
- Add heavy cream 1 tablespoon at a time until you reach the desired consistency.
- Spread the frosting evenly on the cooled cake, create swirls with the back of a spoon, and top with rainbow sprinkles.
Notes
The cake keeps at room temperature for up to 2 days or refrigerated for up to 1 week. Bring to room temperature before serving for best texture and flavor.
If you enjoyed this recipe, try other chocolate favorites from the blog for more decadent ideas and reliable recipes.