This fudgy chocolate sheet cake is deeply moist with an intense chocolate flavor, finished with a silky white chocolate frosting. A decadent treat for white chocolate and chocolate lovers alike.
Rich dark cocoa in the cake layer and creamy white chocolate frosting make this sheet cake extra special. The cake is fudgy and tender, while the white chocolate frosting adds a smooth, sweet contrast. Finished with chocolate shavings or curls, it’s perfect for parties, potlucks, or any time you want a reliably indulgent dessert.
For the Chocolate Cake
This recipe starts with a classic fudgy chocolate cake that holds a slightly springy, moist crumb. The chocolate flavor is amplified by using quality Dutch-processed cocoa powder. Oil, eggs and buttermilk provide lasting moisture and a soft crumb—oil keeps the cake tender even after refrigeration because it stays liquid, and buttermilk reacts with baking soda to help the cake rise.
Freshly brewed strong coffee is stirred into the batter to deepen the chocolate notes. The coffee doesn’t lend a coffee taste to the cake; it simply magnifies the chocolate. If you want to avoid caffeine, substitute boiling water for the coffee.
For the White Chocolate Frosting
The white chocolate frosting is luxuriously creamy and its flavor depends on the quality of the white chocolate you choose. Use a genuine high-quality white chocolate rather than “white cream” or candy melts for the best taste and texture.
Melt the white chocolate slowly—either in a microwave set to medium power in short intervals or over a double boiler—to avoid overheating, seizing or graininess. Let the melted chocolate cool until it’s no longer warm, then incorporate it into softened butter and sifted powdered sugar. Add whipping cream a tablespoon at a time until you reach the desired consistency and sweetness.
For decoration, chocolate shavings or curls add visual contrast and extra chocolate flavor. (If you’d like to make curls, follow a trusted tutorial for best results.)
Recipe Tip
Avoid white chips labeled “white cream” or “white creme” and stay away from candy melts—these lack proper white chocolate flavor and often feel waxy. Choose a high-quality white chocolate for the creamiest, most flavorful frosting.
Make Ahead Tips
To save time, bake the cake the day before serving. Let it cool completely, then cover tightly and store at room temperature or refrigerate overnight. Make the frosting the day you’ll serve for the freshest texture.
If you store the frosted cake in the refrigerator, bring it to room temperature for about 60 minutes before serving so the frosting softens and the cake is at its best. The unfrosted cake can sit at room temperature up to about 8 hours if your kitchen is cool and out of direct sunlight.
- Chocolate Layer Cake
- Mini Chocolate Cake – serves just 4–6 people
- Chocolate Cupcakes
- Flourless Chocolate Cake
Chocolate Cake with White Chocolate Frosting
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Equipment
- 9×13 inch (23 x 33 cm) baking pan*
Ingredients
Chocolate Cake
- 2 cups all-purpose flour (250 grams)
- 1/3 cup cocoa powder (23 grams), Dutch-process
- 2 teaspoons baking soda
- 1 teaspoon baking powder
- 2 cups granulated sugar (400 grams)
- 1/2 cup vegetable oil (120 ml)
- 2 large eggs
- 2/3 cup buttermilk (160 ml)
- 1/3 cup sour cream (80 ml)
- 1 cup freshly brewed coffee (240 ml) (or boiling water)
White Chocolate Frosting
- 6 ounces white chocolate (160 grams)
- 1 cup unsalted butter (225 grams), slightly softened
- 2–3 cups powdered sugar (220–330 grams)
- 1/2 teaspoon salt
- 2–3 tablespoons whipping cream (30–45 ml)
Instructions
Chocolate Cake
- Preheat the oven to 350°F (180°C). Lightly grease a 9×13 inch (23×33 cm) pan and dust with cocoa powder.
- In a large bowl, sift together the flour, cocoa, baking soda, baking powder and salt. Stir in the sugar until evenly combined.
- In a separate bowl, whisk together the oil, eggs, vanilla, buttermilk and sour cream until smooth. Whisk the hot coffee (or boiling water) into the mixture.
- Add the wet ingredients to the dry and beat on low speed for about 1 minute, or whisk by hand until smooth. The batter will be thin.
- Pour into the prepared pan and bake in the center of the oven for 30–40 minutes, or until the top is set and a toothpick comes out clean or with a few moist crumbs. When in doubt, bake a few extra minutes rather than underbaking.
- Remove from the oven and cool completely in the pan.
White Chocolate Frosting
- If using white chocolate bars or baking squares, finely chop the chocolate and place it in a heatproof bowl.
- To melt in the microwave: heat at medium power (about 50%) for 1 minute, stir, then continue in 30-second bursts, stirring between each, until smooth. For a double boiler: place the bowl over gently simmering water, ensuring the water does not touch the bowl, and stir until melted.
- Allow the melted chocolate to cool for at least 15 minutes so it’s not warm when mixed with butter.
- Beat the softened butter until smooth. Add 2 cups sifted powdered sugar and the salt, starting the mixer on low and increasing to medium. Mix in the cooled white chocolate, scraping the bowl as needed. Beat in whipping cream 1 tablespoon at a time until the frosting reaches your preferred thickness and sweetness. Add more powdered sugar if you want a firmer, sweeter frosting.
- Frost the completely cooled cake with an offset spatula or the back of a spoon. Garnish with chocolate shavings or curls if desired.
Notes
- Buttermilk: If you don’t have buttermilk, add 2 teaspoons distilled vinegar or lemon juice to 2/3 cup milk. Let sit 5 minutes before using.
- Coffee: Replace with boiling water if preferred.
- White Chocolate: Use high-quality white chocolate. Avoid “white cream” chips, waxy white chocolate, or candy melts.
- Storage: Store leftovers in an airtight container at room temperature for up to 2 days or refrigerate for up to 4 days. If refrigerated, allow the cake to sit at room temperature about 1 hour before serving so the frosting softens.
- Serving: The recipe yields about 15 slices; because the cake is rich, you may get 18 or more smaller slices.