This rich, moist chocolate walnut cake is loaded with toasted walnuts and finished with a silky whipped dark chocolate ganache. It’s an easy, one-layer snacking cake with a tender crumb—perfect for slicing whenever a chocolate craving strikes.
This recipe is adapted from a classic chocolate cake with ganache. The batter uses both melted butter and neutral vegetable oil to combine rich, buttery flavor with a moist, tender crumb. Because there’s no creaming step, you can make this without a mixer—just simple whisking and folding.
Designed for an 8-inch (20 cm) square pan, this single-layer cake is often called a “snacking cake.” It’s casual and unfussy, easy to put together in a couple of hours, and well suited to everyday dessert or coffee break treats.
Toasted walnuts offer crunchy texture and deepen the nutty flavor in the chocolate batter. The whipped dark chocolate ganache on top keeps sweetness balanced while adding a smooth, luxurious finish. Sprinkle extra toasted walnuts over the ganache for a pretty, crunchy topping.
Ingredients
FOR THE CAKE
See the recipe card below for exact measurements.
Unsalted butter – Melted butter blends smoothly into the batter and contributes rich flavor.
Vegetable oil – Use a neutral oil (canola, grapeseed) so the chocolate flavor remains prominent.
Dutch-process cocoa powder – Alkalized cocoa delivers a darker color and deeper chocolate notes.
Hot coffee – Strong, hot coffee blooms the cocoa and intensifies the chocolate flavor. If you prefer not to use coffee, substitute hot water, hot black tea, or hot milk.
Walnuts – Toast the walnuts before chopping to bring out their best flavor. Spread on a baking sheet and toast at 350°F (177°C) for 5–8 minutes, watching closely to prevent over-browning.
FOR THE GANACHE
Dark chocolate – Use a quality dark chocolate around 60% cocoa for a balanced ganache.
Heavy cream – Heavy cream (heavy whipping cream) provides the fat needed for a stable, thick ganache. Avoid substituting milk or light creams.
Instructions
Photos below illustrate key steps. The concise instructions here follow the recipe card measurements.
Preheat oven to 350°F (177°C). In a medium bowl, sift together the flour, baking soda, and salt. Set aside.
In a large bowl, whisk melted butter, vegetable oil, sugar, and Dutch-process cocoa powder until smooth. Add hot coffee (or hot water) and whisk to combine.
Add eggs one at a time, whisking well after each addition so the batter is smooth and even.
Whisk in the dry ingredients, scraping the bowl to remove any flour pockets. Stir in sour cream and vanilla until the batter is fully blended and silky.
Fold in half of the toasted, chopped walnuts.
Pour the batter into the prepared 8 x 8 inch pan. Rap the pan on the counter to release air bubbles.
Bake on the center rack for 45–50 minutes, or until a toothpick inserted in the center comes out clean and the cake begins to pull away from the pan edges. Cool in the pan for 10–15 minutes, then invert onto a cooling rack and remove the parchment. Cool completely before frosting.
For the ganache: heat heavy cream until it’s just about to simmer. Remove from heat, add finely chopped dark chocolate, and let sit 2–3 minutes. Whisk until smooth and lump-free. Cool the ganache to room temperature; you can speed this by chilling for short intervals and stirring. When the ganache is cooled and thickened, whip it with a whisk attachment until light and fluffy—about 1–2 minutes. Avoid overwhipping to prevent graininess.
Spread the whipped ganache in an even layer over the cooled cake and sprinkle with the remaining toasted walnuts.
Tip: Cool the ganache to room temperature before whipping. Use short refrigeration intervals (10 minutes) with stirring to quicken the process; the ganache should be thick but not cold. Make sure the cake is completely cooled before adding ganache.
Substitutions
Walnuts – Swap walnuts for pecans, hazelnuts, almonds, peanuts, or macadamia nuts if preferred. Toast whatever nut you choose for the best flavor.
Coffee – Use decaffeinated coffee to reduce caffeine, or substitute hot water, black tea, or milk if you prefer no coffee flavor.
Variations
Try these simple variations to change the cake’s profile:
- Espresso ganache – Stir 1–2 teaspoons espresso powder into the cream before adding chocolate for a brighter coffee note.
- Different frosting – Use cream cheese frosting, salted caramel buttercream, or dark chocolate buttercream for a different finish.
- Mix-ins – Fold about ½ cup total of chocolate chips, dried fruit (cherries, cranberries), or shredded coconut into the batter.
Equipment
8-inch square pan – An 8 x 8 inch (20 cm) square metal pan gives clean edges and even heat. If using glass, reduce oven temperature by 25°F and extend baking time slightly to avoid overbaked edges.
Small offset spatula – Helpful for spreading the whipped ganache into a smooth, even layer.
Storage
Store: Keep the cake in an airtight container at room temperature for up to 2 days. After that, refrigerate leftovers covered with foil or plastic wrap.
Freeze: Wrap individual slices in plastic wrap and place in a freezer-safe container for up to 3 months.
Make ahead
You can bake the cake in advance. Once fully cooled, wrap it tightly and freeze for up to 1 month, or store wrapped at cool room temperature for a day or two. Prepare the ganache shortly before serving for best texture, though the entire cake can be assembled up to 24 hours ahead and stored under a cake cover at room temperature.
Frequently asked questions
Ganache is a smooth mixture of chocolate and heated cream. It can be used as a filling, frosting, or glaze. Ganache can be flavored with extracts, liqueurs, or other additions and varies in texture depending on chocolate-to-cream ratio.
Yes, you can substitute natural cocoa. The cake may be slightly lighter in color and flavor. This recipe includes enough baking soda to offset the acidity of natural cocoa, so the texture and rise should remain fine.
Yes. Doubling works well—bake in a 9 x 13 inch pan and start checking for doneness a few minutes earlier than the full recipe time.
Yes. Bake in a 9-inch round pan without changing the recipe; keep the same temperature and check for doneness at the usual time.
Stored in an airtight container, this ganache-topped cake keeps well at room temperature for up to 2 days. Refrigerate beyond that and bring to room temperature before serving for best texture.
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📖 Recipe
Chocolate Walnut Cake
INGREDIENTS
CHOCOLATE CAKE
- Walnuts — 66 grams, toasted and chopped (half for batter, remaining for topping)
- All-purpose flour — 240 grams
- Baking soda — 1 teaspoon
- Kosher salt — 1 teaspoon (Diamond Crystal or similar)
- Unsalted butter — 170 grams, melted
- Vegetable oil — 45 mL (neutral flavor)
- Granulated sugar — 300 grams
- Dutch-process cocoa powder — 30 grams
- Coffee — 240 mL, strongly brewed and hot (or hot water)
- Eggs — 2 large, room temperature
- Sour cream — 120 grams, full fat
- Vanilla extract — 7.5 mL
WHIPPED CHOCOLATE GANACHE TOPPING
- Heavy cream — 180 mL
- Dark chocolate — 170 grams, finely chopped (about 60% cocoa)
- Walnuts — 33 grams, toasted for topping
INSTRUCTIONS
CHOCOLATE CAKE
- Preheat oven to 350°F (177°C). Line an 8 x 8 inch square pan with parchment paper on the bottom and sides.
- Toast all walnuts on a rimmed baking sheet at 350°F for 5–8 minutes, watching carefully. Cool and chop.
- Sift together flour, baking soda, and salt; set aside.
- In a large bowl, whisk melted butter, oil, sugar, and cocoa powder. Add hot coffee and whisk to combine.
- Add eggs one at a time, whisking after each until incorporated.
- Whisk in the dry ingredients, scrape the bowl, then add sour cream and vanilla. Mix until smooth.
- Fold in half of the chopped walnuts. Pour batter into the prepared pan and rap on the counter to remove air bubbles.
- Bake on the center rack for 45–50 minutes, until a toothpick comes out clean and the cake springs back lightly. Cool in the pan 10–15 minutes, then invert onto a rack, remove parchment, and cool completely.
WHIPPED CHOCOLATE GANACHE
- Heat the cream until just about to simmer. Remove from heat and add the chopped dark chocolate. Let sit 2–3 minutes, then whisk until smooth.
- Cool the ganache to room temperature. To speed cooling, refrigerate in short 10-minute intervals, stirring between intervals—do not chill until cold.
- Whip the cooled ganache in a stand mixer with the whisk attachment for about 1–2 minutes until light, fluffy, and holding soft peaks. Avoid overwhipping.
- Spread the whipped ganache evenly over the cooled cake with a small offset spatula. Sprinkle with the remaining toasted walnuts.
NOTES
Cake notes: Toast walnuts for best flavor. Substitute hot water, tea, or milk for coffee if preferred.
Pan sizes: This recipe works in a 9-inch round pan without change. To double the recipe, bake in a 9 x 13 inch pan and begin checking for doneness a few minutes early.
Whipped ganache: The whipped ganache should be lighter in color and fluffy. Stop when it holds peaks—overmixing can make it grainy.
Storage: Keep at room temperature up to 2 days in an airtight container; refrigerate after that. Freeze slices wrapped for up to 3 months.
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