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Killer chocolate cake recipe for a truly indulgent dessert

This decadent Killer Chocolate Cake is a must-try for any chocolate lover and a delightful addition to the vegetarian dessert repertoire. Richly flavoured with semisweet chocolate and a hint of vanilla, this cake boasts a moist texture that melts in the mouth. The combination of unsalted butter and buttermilk ensures that every bite is indulgent, while the addition of cocoa powder gives it that classic chocolate richness that’s simply irresistible.

Ideal for special occasions or a sweet afternoon treat, this cake is sure to impress both family and friends. With the perfect balance of sweetness from light brown sugar and a subtle depth from a touch of soy sauce, it makes for a comforting dessert that pairs beautifully with a dollop of cream or a scoop of vanilla ice cream. Whether served at a birthday party or a quiet weekend gathering, this vegetarian chocolate cake is a timeless treat that everyone will enjoy.

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Ingredients for Killer chocolate cake

  • 225 g unsalted butter, at room temperature

  • 280 g plain flour

  • 45 g cocoa powder

  • 7 g baking powder

  • 2 g baking soda

  • 3 g fine sea salt

  • 400 ml buttermilk

  • 10 ml pure vanilla extract

  • 450 g light brown sugar

  • 3 large eggs

  • 225 g semisweet or bittersweet chocolate, finely chopped, melted (see Note)

  • 150 g unsalted butter, at room temperature

  • 120 g icing sugar

  • 115 g bittersweet chocolate, finely chopped, melted, cooled to room temperature (see Note)

  • 30 ml soy sauce

  • 5 ml pure vanilla extract

How to make Killer chocolate cake

  1. Preheat the oven to 180°C. Grease a 23 x 33 cm (9 x 13 inch) glass or metal cake pan with 15 g of room temperature butter.

  2. Whisk together the flour, cocoa powder, baking powder, baking soda, and salt in a large bowl.

  3. Combine the buttermilk and vanilla in a medium bowl or a 500 ml liquid measuring jug.

  4. In the bowl of a stand mixer fitted with the paddle attachment (or in a large bowl if using a handheld mixer), cream together the butter and brown sugar on low speed until creamy and well combined.

  5. Increase the speed to medium-high and beat until light and airy, for about 2 minutes.

  6. Reduce the mixer speed to medium-low and add the eggs one at a time, mixing well between each addition and scraping down the sides and bottom of the bowl as needed.

  7. Once all three eggs are added, beat for 1 minute on medium speed to achieve a fluffy mixture.

  8. Reduce the speed to medium-low and add the flour mixture alternately with the buttermilk mixture in three batches, starting with the flour.

  9. Add the melted chocolate and mix on medium speed until well incorporated, stopping the mixer to scrape down the sides and bottom of the bowl as needed.

  10. Use a rubber or offset spatula to scrape the batter into the prepared pan and level it out as much as possible.

  11. Bake for about 40 minutes, or until a cake tester inserted into the centre of the cake comes out clean and the centre resists light pressure.

  12. Remove from the oven and set aside to cool completely, for at least 2 hours, before frosting.

  13. To make the frosting, put the butter in the bowl of a stand mixer fitted with the whisk attachment (or in a medium bowl if using a handheld mixer). Beat on medium-high speed until smooth.

  14. Turn off the mixer and sift the icing sugar into the bowl, then combine on low speed.

  15. Add the melted chocolate, soy sauce, and vanilla, and beat on low speed until combined.

  16. Increase the mixer speed to medium-low and whip until glossy, for 15 to 30 seconds.

  17. Use an offset spatula or butter knife to spread the frosting on top of the cooled cake.

  18. Cut into squares and serve.

  19. DO AHEAD: The cake will keep, loosely covered with cling film in the refrigerator, for up to 3 days. Let it sit at room temperature for 15–20 minutes before slicing and serving.

Disclaimer
While every effort has been made to ensure the information is accurate and up to date, individual needs may vary and dietary requirements can differ based on personal health conditions. Always check food labels and allergen information before preparing or consuming any recipe. If you have specific health concerns, allergies, intolerances, or are following a medically prescribed diet, seek advice from your GP, pharmacist, or a registered dietitian before making significant changes to your diet or lifestyle.

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Article history

The information on this page is peer reviewed by qualified clinicians.

  • 17 Jul 2025 | Originally published

    Authored by:

    UK recipe editors

    Peer reviewed by

    UK recipe editors
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