This is the most delicious chocolate walnut cake – snack cake sized! It’s covered in the dreamiest dark chocolate sour cream frosting and sprinkled with chopped walnuts. It only takes 15 minutes to prepare this cake, plus no mixer required for the cake!
Sometimes you don’t want a layer cake, as much as I love my chocolate orange layer cake, and want something simple like a snack cake.
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Tell me about this recipe!
- This easy cake is based off my simple oil based chocolate cake, no need to cream butter and no mixer required!
- Just before baking, the batter is folded with finely chopped walnuts.
- This chocolate walnut cake is topped with a super fudgy dark chocolate sour cream buttercream, and then sprinkled with chopped walnuts. I love this buttercream because it isn’t too sweet.
Ingredients Needed
Chocolate Walnut Cake Ingredients 
Chocolate Frosting Ingredients
The printable recipe card with the full list of ingredients and instructions can be found at the bottom of this post.
- Oil: Use a neutral oil in the cake, like canola, vegetable or rapeseed oil. This will make the cake extra moist and no need to cream butter!
- Coffee: I add hot coffee to the cocoa powder which will bloom it, making the chocolate extra dark and chocolatey!
- Melted Dark Chocolate: try to use good quality chocolate for the frosting, it will make a huge difference!
How to make this recipe
Step One: Whisk together your sugar and egg for 1 minute until you have a few bubbles. Add the buttermilk, hot coffee, oil, vanilla and salt and mix again.
Step Two: Add your cocoa powder and whisk until smooth. Add your flour, baking powder, baking soda and chopped walnuts and fold until there are no pockets of flour. Pour into an 8×8 greased and lined pan and bake for 35-45 minutes at 350 degrees.
Step Three: Beat your butter and confectioners’ sugar together on low speed in your stand mixer or with a hand mixer until well combined. Turn the speed to high and mix for 2-3 minutes until fluffy.
Step Four: Add in your cocoa powder and mix on low until the cocoa powder is combined – this stops it from flying everywhere! Increase the speed to medium and mix for 1-2 minutes. Pour in your sour cream, melted chocolate and salt and mix once more. Use immediately.
Expert Tips
- I highly recommend using a weighing scale and measuring out your ingredients the metric way. It makes a huge difference to your baking and is the most accurate way to bake!
- I make sure that all of my ingredients are at room temperature before I start the recipe, so pull out all of the ingredients (including the buttermilk!) before you start baking.
- Make sure your walnuts are finely chopped, I use my food processor to do this but you could also place them in a large ziplock bag and crush them with a rolling pin. If the walnuts are too large, they might sink in the chocolate walnut cake.
Frequently Asked Questions
Yes! So you can substitute the buttermilk for sour cream or full fat yoghurt, or you could make your own buttermilk. For every cup of milk, add 1 tablespoon of vinegar or lemon juice. Mix, then let sit for 5 minutes before using.
You can! Make it in a 9 inch round pan and bake for the same amount of time.
Keep it tightly wrapped and in the fridge for up to 5 days. When ready to eat, let it sit at room temperature so the frosting can soften, as it does harden in the fridge.
Other Cake Recipes
Have you made this recipe? Make sure to tag me on Instagram @alpineella and leave a review below if you have! If you want more baking ideas, you can follow me on Pinterest.
Recipe
Chocolate Walnut Cake
Equipment
- 8×8 inch cake pan
Ingredients
Walnut Chocolate Cake
- 120 ml hot coffee
- 32 grams cocoa powder dutch processed
- 175 grams granulated sugar
- ¼ teaspoon vanilla extract
- ½ teaspoon kosher salt
- 1 egg room temperature
- 110 grams all purpose flour
- 1 teaspoon baking soda
- ½ teaspoon baking powder
- 120 ml buttermilk room temperature
- 60 ml vegetable oil
- 64 grams walnuts finely chopped
Chocolate Frosting
- 110 grams unsalted butter room temperature
- pinch kosher salt
- 113 grams confectioners' sugar
- 42 grams cocoa powder dutch processed
- 60 ml sour cream room temperature
- 85 grams dark chocolate chopped
Instructions
Make Cake
- Preheat your oven to 350°F/175°C. Butter or grease an 8 inch square baking pan and line it with parchment paper.
- In a large bowl, whisk together the sugar and egg for 1 minute.
- Add the buttermilk, hot coffee, oil, vanilla and salt. Whisk until it is smooth. Add your cocoa powder and whisk again until smooth
- Add the flour, baking powder, and baking soda and whisk until smooth. Fold in your chopped walnuts
- Pour into your pan and tap on the counter to get rid of any bubbles. Bake for 35-45 minutes. A toothpick inserted should come out clean. Allow it to cool for 20 minutes in the pan, then lift it out and let it cool completely on a cooling rack.
Make Frosting
- Melt your chocolate in a microwave, stirring every 10 seconds so it doesn't burn.
- In your stand mixer with the paddle attachment, beat the butter and confectioners’ sugar on low speed until well combined
- Turn the speed to high for 2-3 minutes until light and fluffy.
- Add in your cocoa powder and beat on low, then increase the speed to medium for 1-2 minutes.
- Add your sour cream, melted chocolate and salt and mix once more.
- Spread over your cooled cake and decorate with walnuts.
Alison
Ohhhh so decadent and delicious!!
Ella
thank you!!
Kelley
May taste ok, but this recipe is organized so poorly it’s nearly impossible to follow. I must have scrolled 50+ times just to keep track of the mixing instruction and ingredients.
November
I am scaling up this recipe by four, would you recommend doing the same with baking soda and powder (using 4 teaspoons soda and two teaspoons powder)?
Ella
Hi! I haven’t tested that but it should work!
Sharon
I made this recipe (cake only) on New Year’s Day and it turned out to be a hit. I used a cream cheese and whipped cream icing as I prefer the taste over buttercream. Thank you Ella. This one’s a keeper for certain.
Ella
Thanks so much for your review, so glad you liked it! The icing you used sounds delicious!
Judy Kahn
Your cake looks divine. For the dark chocolate, what percent chocolate do you recommend? Thanks!
Ella
Thank you! I usually use the Lindt 51% baking chocolate!
jon
looks great! I would replace the vegetable oil with ghee for buttery upgrade that works great with cake
Ella
I’ve never tried it with ghee, need to give that a try!
Natalie
THIS WAS FANTASTIC!! Kids to adults went nuts over this especially the frosting. In my humble opinion, the cake gets better as it sits so next time I’ll make the cake the day before and frost right before serving!
Ella
Thank you so much Natalie for this review!
Nicola
Excellent recipe. So easy to make.