This rich, moist chocolate walnut cake is packed with toasted walnuts and topped with a velvety smooth whipped chocolate ganache. It's an easy, one layer snacking cake. You'll find yourself slicing another piece every time you walk by!
This recipe is adapted from my easy chocolate cake with ganache.
The cake batter is made with both oil and melted butter for the best combination of buttery taste and moist, tender crumb. There's no creaming required, so it's a simple recipe to make without a mixer.
It's an 8 inch (20 centimeter) square single layer cake. This style of cake is frequently referred to as a "snacking cake." It's a no-fuss recipe that you can put together in a few hours, and has a more casual feel than a layer cake.
The toasted walnuts add a crunchy texture and roasted nutty flavor to the chocolate cake. A blanket of whipped dark chocolate ganache frosting on top keep this cake from being too sweet. Extra toasted walnuts adorn the cake and add extra bite and a pretty decoration.
For more chocolate cakes, try this citrus-forward chocolate and orange cake, and this olive oil chocolate bundt cake with chocolate ganache. They use similar variations of this simple chocolate cake recipe.
For an extra fancy layer cake with nuts, try this chocolate chestnut cake with layers of velvety chocolate chestnut mousse.
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Ingredients
FOR CAKE
* See recipe card for full list of ingredients and quantities.
Unsalted butter - Melted butter is easy to incorporate and doesn't require using a mixer!
Vegetable oil - I prefer using a neutral vegetable oil (such as canola or grapeseed) in order to let the chocolate flavors stand out.
Dutch process cocoa powder - This recipe calls for Dutch process (alkalized) cocoa powder for the darker color and more intense chocolate flavor.
Coffee - I use freshly brewed, hot coffee as the liquid in the cake batter. If you prefer not to use coffee, substitute hot water, hot black tea or even hot milk. Using a hot liquid is a great trick to help the cocoa powder "bloom" by dissolving the cocoa powder and releasing additional flavor.
Walnuts - Use toasted walnuts in order to bring out their best flavor. If yours are not toasted, chop them finely, place on a baking sheet and bake in a 350 degree oven for 5-8 minutes, monitoring frequently to keep them from browning too much.
FOR GANACHE
Dark chocolate - For the ganache, I use a dark chocolate with 60% cocoa.
Heavy cream - Use heavy cream or heavy whipping cream. Do not substitute with milk, half and half, or other similar consistency non-dairy milks as they don't have the fat content required to create a thick ganache.
Instructions
These photos provide visual cues. Find the detailed instructions in the recipe card.
In a medium bowl, sift together flour, baking soda and salt. Set aside.
In a large mixing bowl, whisk together melted butter, oil, sugar and cocoa powder.
Add hot coffee (or water) and whisk to combine. Add eggs one at a time, whisking well between additions to ensure they are fully incorporated.
Add dry ingredients and whisk again. Scrape bowl with spatula to ensure no flour pockets remain. Add sour cream and vanilla. Whisk until completely blended and batter is smooth.
Fold in ½ cup of the toasted, chopped walnut pieces.
Pour batter into prepared pan. Rap pan firmly on countertop to remove air bubbles that may have formed in batter.
Bake for 45-50 minutes. Cool in pan for 10 minutes, then invert onto rack and remove parchment. Let fully cool.
Heat cream until almost simmering. Remove from heat. Add finely chopped dark chocolate. Let sit for 3 minutes. Whisk ganache mixture until no lumps remain. Cool until room temperature and thickened. Once cool, beat ganache in bowl of stand mixer fitted with whisk attachment until light and fluffy, about 1-2 minutes.
Spread the whipped ganache in an even layer over the cake. Sprinkle with remaining toasted walnuts.
Hint: For the whipped chocolate ganache, cool the ganache until room temperature / set. You can quicken this process by placing the ganache in the refrigerator for 10 minute intervals, stirring after each. It should be ready in 20-30 minutes. When beating, do not overwhip or the ganache may turn grainy. Make sure the cake is fully cooled before adding ganache.
Substitutions
- Walnuts - If you're not a fan of walnuts or have an allergy but still want a nutty chocolate cake, consider subbing them for pecans, hazelnuts, almonds, peanuts or macadamia nuts. Don't forget to toast them for maximum flavor.
- Coffee - To reduce the caffeine, feel free to use decaffeinated coffee. If you'd rather avoid coffee completely, substitute water, black tea or even milk.
Variations
While this cake is delicious as is, feel free to choose one of the following variations:
- Espresso ganache - add 1-2 teaspoons of espresso powder to the heavy cream before making the ganache.
- A different frosting - If you'd like to try a different topping, consider using cream cheese frosting, salted caramel buttercream, or dark chocolate buttercream.
- Mix-ins - An aditional ingredient in the batter will give your cake a unique twist. Try adding about ½ cup total of the following:
- Chocolate chips
- Dried fruit (cherries, cranberries...)
- Shredded coconut
Equipment
Square metal pan - I use this 8 x 8 x 2.25 inch nonstick metal pan to bake most of my square cakes and bar cookies.
Glass and metal pans conduct heat differently. Glass bakeware takes longer to heat up than metal pans, and retains heat for longer once hot. Using a glass pan without adjusting this recipe might result in overbaked edges. The batter will take longer to cook, and might bake too much on the edges.
If you only have a glass pan, you may need to experiment with lowering the heat by 25 degrees Fahrenheit and baking for an additional 10 minutes. King Arthur Baking has visual examples of recipes tested using different pans here.
Small offset spatula - A small offset spatula makes spreading the whipped ganache very easy. It's an indispensable tool for frosting cakes too.
Storage
Store: Store this cake in an airtight container at room temperature for up to 2 days. After that, store any leftovers in the refrigerator covered with aluminum foil or plastic wrap.
Freeze: Wrap individual slices of cake in plastic wrap and store in a zippered bag or airtight container in the freezer for up to 3 months.
Make ahead: Although this is a straightforward cake to make, it's always helpful to break a recipe up into smaller steps.
Bake the cake in advance. Once cake is fully cooled, wrap well in plastic wrap and place in an airtight container or zippered storage bag in the freezer for up to 1 month. If you're simply baking the cake layer a day or two in advance, wrap it and store at cool room temperature.
It's best to make the ganache immediately before adding it to the cake. If desired, you can make the entire cake 24 hours in advance. Store under a cake cover at room temperature.
Frequently asked questions
Ganache is a smooth mixture of chocolate and heavy cream that is made by melting the chocolate in the heated cream. It is used as a filling, frosting, or glaze for cakes, pastries, and other desserts.
It can be made with different types of chocolate, and can be flavored with various ingredients like liqueurs, extracts or fruit purees.
This recipe uses Dutch process cocoa powder for a darker color and deeper chocolate flavor.
Don't have any? You can most likely substitute with natural cocoa powder here. There's enough baking soda in this recipe that it should neutralize the added acidity from natural cocoa powder and also provide the needed leavening.
That said, since natural cocoa powder is lighter in color and flavor, you may find that the cake is lighter in both color and flavor.
My preference is to stick with Dutch process cocoa for this recipe.
Yes. You can easily double this recipe using the 2x button in the recipe card. You'll use a 9 x 13 pan to bake the cake. Start checking the cake 5-10 minutes earlier.
Yes, you can make this in a 9" round pan without any changes to the recipe. Keep the baking time and temperature the same.
If you double the recipe, you can create a chocolate walnut layer cake with two 9" layers. There is enough ganache to frost the top of both layers, leaving the sides bare.
A ganache cake can generally be safely stored at room temperature for up to 2 days. If you're concerned, feel free to place the cake in the refrigerator. Just bring it to room temperature before serving for best texture and flavor.
Love this recipe? Please leave a comment and star rating. ★★★★★ Your feedback, suggestions, and adaptations are very helpful to other bakers!
📖 Recipe
Chocolate Walnut Cake
INGREDIENTS
CHOCOLATE CAKE
- 240 grams (2 cups) all purpose flour
- 1 teaspoon baking soda
- 1 teaspoon kosher salt
- 170 grams (¾ cup; 6 ounces) unsalted butter, melted
- 45 mL (3 Tablespoons) vegetable oil, neutral flavor
- 300 grams (1½ cups) granulated sugar
- 30 grams (¼ cup + 2 Tablespoons) cocoa powder, Dutch process
- 250 mL (1 cup) coffee, strongly brewed, hot
- 2 large eggs, room temperature
- 120 grams (½ cup) sour cream, full fat
- 1½ teaspoons vanilla extract
- 66 grams (½ cup) walnuts
WHIPPED CHOCOLATE GANACHE TOPPING
- 188 mL (¾ cup; 6 ounces) heavy cream
- 170 grams (6 ounces) dark chocolate, finely chopped, I used a 60% chocolate bar
- 33 grams (¼ cup) walnuts, to sprinkle on top of cake
INSTRUCTIONS
CHOCOLATE CAKE
- Preheat oven to 350° F (177° C, Gas Mark 4).
- Line the bottom and sides of an 8 inch (20 centimeter) square cake pan with parchment paper.
- Toast all walnuts for both cake and topping. Chop walnuts into small pieces and place on a rimmed baking sheet. Bake at 350° F for 5-8 minutes, watching carefully to avoid browning them too darkly (they'll get bitter). Set aside to cool.
- In a medium bowl, sift together flour, baking soda and salt. Set aside.240 grams (2 cups) all purpose flour, 1 teaspoon baking soda, 1 teaspoon kosher salt
- In a large mixing bowl, whisk together melted butter, vegetable oil, sugar and cocoa powder. Mix well and add hot coffee (or water) and whisk to combine.170 grams (¾ cup; 6 ounces) unsalted butter, 45 mL (3 Tablespoons) vegetable oil, 300 grams (1½ cups) granulated sugar, 30 grams (¼ cup + 2 Tablespoons) cocoa powder, 250 mL (1 cup) coffee
- Add eggs one at a time, whisking well between additions to ensure they are fully incorporated.2 large eggs
- Add dry ingredients and whisk again. Scrape the bowl with a spatula to ensure no flour pockets remain. Add sour cream and vanilla, and whisk until completely blended and batter is smooth.120 grams (½ cup) sour cream, 1½ teaspoons vanilla extract
- Fold in ½ cup of the toasted, chopped walnut pieces. Pour batter into prepared pan. Rap pan firmly on countertop to remove air bubbles that may have formed in batter.66 grams (½ cup) walnuts
- Bake in center rack of oven for 45-50 minutes, until a toothpick inserted in the middle comes out clean, cake bounces back lightly when touched with a finger, and cake is beginning to pull away from the edges of the pan.
- Cool cake in pan for 10-15 minutes, then invert onto a cooling rack and remove parchment. Cool cake completely. Once cool, transfer to a serving platter.
WHIPPED CHOCOLATE GANACHE
- In a microwave safe container or small (1 quart) saucepan, heat cream until almost simmering. Remove from heat and add finely chopped dark chocolate. Let sit for 2-3 minutes, then whisk until all chocolate has melted and no lumps remain.188 mL (¾ cup; 6 ounces) heavy cream, 170 grams (6 ounces) dark chocolate
- Let cool until room temperature. You can expedite the cooling process by placing the container in the refrigerator for two or three 10 minute intervals. Whisk every 10 minutes. You don't want it COLD. Just use the fridge to reach room temperature more quickly.
- Add cooled ganache to the bowl of a stand mixer fitted with the whisk attachment. Whisk for 1 minute on high, scraping down the bowl several times to make sure the chocolate is evenly whipped. Whipped ganache should be duller, much lighter in color, fluffy, and hold firm peaks when the whisk is lifted out. Do not overmix or it might become grainy.
- Using a small offset spatula, spread the whipped ganache in an even layer over the top of the cake. Leave the sides bare.
- Sprinkle the top of the cake with the remaining ¼ cup toasted walnuts.33 grams (¼ cup) walnuts
EQUIPMENT
NOTES
- Toast your walnuts to bring out the richest flavor.
- If you don't drink coffee, feel free to replace it with hot water, black tea or milk.
- You can bake this cake in a 9 inch round pan without any changes to the recipe. Keep the baking time the same.
- Double this chocolate and walnut cake recipe using the 2x button in the recipe card. You'll use a 9 x 13 inch pan to bake the cake. Start checking the cake 5 minutes earlier, at the 40 minute mark.
- Whipped ganache should be duller, much lighter in color, fluffy, and hold firm peaks when the whisk is lifted out. Do not overmix or it might become grainy.
- Store this cake in an airtight container at room temperature for up to 2 days. After that, store any leftovers in the refrigerator covered with aluminum foil or plastic wrap.
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