This Chocolate Walnut Cake is a delicious mash up of moist chocolate cake with a nice nutty flavor. It's made in one bowl and topped with the most fluffy and luscious homemade chocolate buttercream frosting. It's also a single layer snack cake, so it's easy as can be and perfect for any occasion - holiday, birthday, or really just about any get-together.
There really is nothing quite like homemade chocolate cake - and this chocolate walnut cake is made with some relatively staple ingredients:
- All purpose flour: This is my go-to flour always. Standard and easy to work with.
- Granulated sugar: This cake needs sugar - both the unsweetened cocoa and the walnuts are on the bitter side, so this balances it out.
- Whole milk: Moisture! I would not swap any other milk.
- Vegetable oil: Really any neutral oil works - vegetable, canola, etc.
- Eggs: Binds the cake together and gives it moisture.
- Vanilla extract: I typically add this into my cakes; it adds great flavor without overpowering.
- Unsweetened cocoa powder: A must in chocolate cake, of course.
- Baking soda & baking powder: Both of these leavening agents are necessary for the perfect rise. They work together!
- Espresso powder: This really brings out the chocolate flavor and makes it more rich.
- Ground walnuts: Regular walnuts - not roasted or salted. I like to use a food processor and pulse the walnuts up a bit to get them nice and fine.
- Hot water: Adding hot water "blooms" the espresso to bring the flavor out.
- Salt: Always, for balance.
And for the chocolate buttercream:
- Unsalted butter: The star of the show. I always like to use unsalted so that I can fully control the salt. Salted is fine, just taste before adding more salt. Room temp is crucial.
- Unsweetened cocoa powder: The other star of the show.
- Powdered sugar: This is where the sweetness comes in. You can add more or less to your taste.
- Vanilla extract: Adds great flavor.
- Whole milk: This thins it out a little bit to help it get nice and fluffy.
- Salt: To balance out the sweetness.
Step by step instructions
PREP: Preheat your oven to 350℉. Get your 8x8 baking pan and spray with non-stick spray, and line with parchment paper.
1. Combine the eggs and sugar. In a large bowl, whisk together the eggs and sugar until light pale yellow.
2. Add the remaining wet ingredients (except the water). Then whisk in the vanilla, vegetable oil, and milk.
3. Add dry ingredients (except flour and walnuts). To the same bowl, whisk in cocoa powder, baking powder, baking soda, salt, and espresso powder.
4. Add walnuts. Gently whisk in the walnuts to the cake mixture.
5. Add flour. Whisk in the flour until just combined. Do not over mix! It's ok to see a few streaks of flour because you're going to whisk a bit more when adding the water.
6. Add water. In a steady stream, slowly whisk in the hot water until combined.
7. Bake! Pour the batter into your prepped 8x8 baking pan and bake at 350℉ for 20-30 minutes until a cake tester or tooth pick comes out clean. It's a large time window, but good to start checking at 20 minutes to not over-bake the cake.
8. Start making the buttercream. While the cake is baking, in a mixer with a paddle attachment whip the (room temp!!) butter for about 3 minutes. This can also be done with an electric hand mixer, or by hand with a bit of elbow grease.
9. Add cocoa powder, salt, vanilla. Add in the cocoa powder, salt, and vanilla. Whip again until combined, then add in the powdered sugar - it will look dry.
10. Add the milk. Finish it off with the milk and whip until smooth and fluffy.This can also be done with an electric hand mixer, or by hand with a bit of elbow grease.
11. Finish the cake. When the cake is done baking, let it sit in the pan for a few minutes, then remove and cool to room temp. Once it's at room temp, frost the cake, slice, and serve!
Tips and tricks
- Use a food processor to grind the walnuts! I like to put them in and chop them up quickly. You can do this by hand but you want them pretty fine, so food processor is easier.
- Use regular walnuts! Not roasted, not salted, just regular walnuts.
- Use room temp ingredients! This helps make sure that they all combine together really seamlessly for the best cake. It's especially important for the buttercream because the butter won't whip the same if it's cold. More on why this is important here.
- Don't over mix! I know I mentioned it in the directions, but it's really important to not over mix the cake, it will make it it tough and over work the gluten.
- Test the cake when it's almost done baking! When the cake is in the oven nearing done, test it using a toothpick and see where it's at to help gauge how much more time it needs in the oven. You want a toothpick to come out clean or with a few crumbs.
If you used the proper amount of baking soda and baking powder, it's most probable that your cake didn't rise because of old leavening ingredients. If these have been open for more than 4-6 months, they need to be replaced.
Espresso and coffee really help bring out and maximize the chocolate flavor in cakes. You don't taste the espresso at all (I personally do not like coffee, but love this cake).
The texture! Chocolate fudge cake has a thicker consistency and usually uses chocolate chips/bar of chocolate in the batter.
Yes! You can easily make this a 8x8 round cake (baking time would be the same), or a loaf cake (baking time would be a bit longer - closer to 40-50 minutes.
It's best stored in an air-tight container in the fridge for up to 4 days, or in the freezer sealed for up to 3 months.
More chocolate recipes
- Chocolate Peanut Butter Rice Krispies Treats
- Double Chocolate Banana Bread
- Fluffy Chocolate Chip Muffins
- Chocolate Krispie Peanut Butter Shortbread Bars
Chocolate Walnut Cake
For the cake
- 2 large eggs
- 1 cup granulated sugar
- ½ cup whole milk
- ½ cup vegetable oil
- 1 teaspoon vanilla extract
- ½ cup unsweetened cocoa powder
- 1 teaspoon baking powder
- ½ teaspoon baking soda
- ½ teaspoon kosher salt
- ½ teaspoon espresso powder
- ½ cup ground walnuts
- 1 cup all purpose flour
- ½ cup boiling water
For the chocolate buttercream
- ½ cup unsalted butter room temp
- ¼ cup unsweetened cocoa powder
- ½ teaspoon vanilla extract
- ¼ teaspoon kosher salt
- 1 ½ cups powdered sugar more or less to taste
- 2 tablespoon whole milk
To make the cake
- Preheat your oven to 350℉ and line and spray a 8x8 baking pan.
- In a large bowl, whisk together the eggs and sugar until light pale yellow.
- To the egg and sugar mixture, add the milk, vegetable oil, and vanilla and whisk to combine.
- To the same bowl, whisk in cocoa powder, baking powder, baking soda, salt, and espresso powder.
- Gently whisk in the ground walnuts.
- Then whisk in the flour until just combined. Do not over mix! It's ok to see a few streaks of flour because you're going to whisk a bit more when adding the water.
- Lastly, in a steady stream, slowly whisk in the boiling water until combined.
- Pour the batter into your prepped 8x8 baking pan and bake at 350℉ for 20-30 minutes until a cake tester or tooth pick comes out clean. It's a large time window, but good to start checking at 20 minutes to not over-bake the cake.
- When the cake is done baking, let it sit in the pan for a few minutes, then remove and cool to room temp.
To make the chocolate buttercream
- While the cake is baking, in a mixer with a paddle attachment whip the (room temp!!) butter for about 3 minutes.
- Add in the cocoa powder, salt, and vanilla. Whip again until combined, then add in the powdered sugar.
- Once that's combined (it will look dry), add in the milk and whip again until smooth and fluffy - a few more minutes.
To finish the cake
- Once the cake Is at room temp dollop on the frosting and spread it around evenly. Top with chopped walnuts (optional), and serve!