Keto Chocolate Fudge Cake with Ganache
This easy keto chocolate cake is a rich fudge cake made with Groovy Keto Chocolate Cake Mix, eggs and butter, with chopped dark chocolate buttons stirred through and a glossy dark chocolate ganache poured over the top. Each slice has 1.8g net carbs. It takes 50 minutes, plus cooling and setting.
This keto chocolate cake borrows from some proven recipes. Benjamina Ebuehi's chocolate fudge cake on BBC Food gives us our ganache method: heat the cream until it's steaming, pour it over chopped chocolate, leave it briefly and then stir from the middle outwards, and only ice the cake once it's completely cool. BBC Good Food's chocolate ganache recipe suggests a pinch of sea salt or a splash of espresso to deepen the chocolate flavour, so we've added the salt and kept the coffee as a variation. Texas Granola Girl's keto chocolate cake with ganache stirs chopped chocolate chips into the batter and lets the ganache spill over the edges, which is how we finish ours. We've brought those ideas together with our own cake mix and chocolate buttons.
The result is a dark, moist, fudgy cake with a soft, glossy topping. A slice of shop-bought chocolate fudge cake the same size has about 34.5g carbohydrate; a slice of this one has 1.8g net carbs. If you're searching for sugar free chocolate cake, this one has no added sugar: it's sweetened with erythritol and stevia, and the small amount of sugars comes from the cocoa, almonds and dairy. To find out which kinds of chocolate work on keto, read our guide Is chocolate keto-friendly?
What we used: Groovy Keto Chocolate Cake Mix for the sponge, which only needs eggs, butter and water, and Groovy Keto Dark Chocolate Buttons, chopped into the batter and melted with cream for the ganache. The pack's own figure of 1g net carbs per slice is for the plain cake; the extra chocolate and the ganache take it to 1.8g. For other flavours, see our keto baking mixes.
Groovy Keto Chocolate Cake Mix
View product
Groovy Keto Dark Chocolate Buttons
View productKeto chocolate cake vs ordinary chocolate fudge cake
Ordinary chocolate fudge cake is made with wheat flour and sugar, and usually a sugary fudge icing, so most of its carbohydrate is starch and sugar. This one uses a mix made with almond flour, coconut flour and cocoa, sweetened with erythritol, and erythritol counts as a polyol, which UK labels list within carbohydrate.
| Per slice (about 62g) | Carbohydrate | Sugars | Net carbs |
|---|---|---|---|
| Chocolate fudge cake, shop-bought | 34.5g | 27.0g | 34.5g |
| This keto chocolate cake | 16.4g | 0.7g | 1.8g |
Ordinary chocolate fudge cake figures are worked out for a 62g slice, about the weight of one of our slices with ganache, from UK CoFID 2021 data (food code 11-527, "Cake, chocolate fudge": 55.7g carbohydrate and 43.5g sugars per 100g) – McCance and Widdowson's composition of foods. Carbohydrate excludes fibre, as on UK labels. Our carbohydrate figure includes 14.6g polyols from the erythritol, which are taken off to give net carbs.
Tips for a moist keto chocolate cake
- Use room-temperature eggs. Cold eggs can set the melted butter into little lumps. Take them out of the fridge 30 minutes before you start.
- Chop the buttons small. Pieces about the size of a pea stay suspended in the thick batter and leave soft, fudgy pockets of chocolate in each slice.
- Don't overbake. The cake firms up as it cools, so take it out as soon as a knife comes out clean. An overbaked keto sponge turns dry.
- Keep the cream below boiling. Very hot cream can make the ganache split. Steaming is hot enough to melt the chocolate.
- Wait for a cold cake. Ganache poured over a warm cake melts and slides off. Cool the cake completely first.
- Use a hot knife. Dip a sharp knife in hot water and wipe it dry between cuts for neat slices with a clean ganache edge.
Keto Chocolate Fudge Cake with Ganache
- Prep time15 min
- Bake time30–35 min
- Total time50 min, plus cooling and setting
- Serves12 slices
- Net carbs1.8g per slice
Ingredients
For the cake
- 1 pack (260g) Groovy Keto Chocolate Cake Mix
- 3 large eggs, at room temperature
- 100g unsalted butter, melted and cooled slightly
- 1 tablespoon water
- 50g Groovy Keto Dark Chocolate Buttons, roughly chopped
For the ganache
- 100g Groovy Keto Dark Chocolate Buttons
- 100ml double cream
- 10g unsalted butter
- a pinch of fine sea salt
You will also need a 20cm round cake tin, baking paper, a large bowl, a small pan, a heatproof bowl, a wire rack and a palette knife.
Method
- Heat the oven. Heat the oven to 180°C (160°C fan, gas mark 4). Grease a 20cm round cake tin and line the base and sides with baking paper.
- Mix the wet ingredients. In a large bowl, whisk the eggs, melted butter and water together with a fork or balloon whisk until smooth.
- Add the cake mix. Tip in the cake mix and stir with a wooden spoon or spatula until there are no dry pockets left, then fold the chopped chocolate buttons through. The batter will be thick.
- Bake. Spread the batter evenly in the tin and bake on the middle shelf for 30 to 35 minutes, until the edges are firm and a knife pushed into the centre comes out clean. Start checking at 30 minutes, as ovens vary.
- Cool. Leave the cake in the tin for 15 minutes, then turn it out onto a wire rack, peel off the paper and leave it to cool completely, which takes about 1 hour.
- Make the ganache. Put the 100g chocolate buttons and the butter in a heatproof bowl. Heat the cream in a small pan until it's steaming but not boiling, then pour it over the chocolate. Leave it for 1 minute, add the salt and stir slowly from the centre outwards until smooth and glossy.
- Let it thicken. Leave the ganache at room temperature for 10 to 15 minutes, stirring now and then, until it coats the back of a spoon but still pours.
- Pour and set. Sit the cake, still on its rack, over a tray. Pour the ganache onto the centre and nudge it towards the edges with a palette knife so it drips down the sides. Leave it to set for 30 minutes, then lift the cake onto a plate and cut it into 12 slices.
How to serve keto chocolate cake
- With cream: serve each slice with a spoonful of thick double cream or softly whipped cream.
- With berries: a few fresh raspberries on the side cut through the richness of the ganache.
- Warm as a pudding: warm a slice for 15 seconds in the microwave so the ganache turns soft and saucy.
- At a party: serve it alongside our keto Victoria sponge, or find more ideas in our round-up of keto sweet treats.
Storage and freezing
- Room temperature: keep the cake in an airtight tin in a cool place for up to 2 days.
- Fridge: it keeps in an airtight box in the fridge for up to 5 days. The ganache firms up when chilled, so let slices sit at room temperature for 20 minutes before serving.
- Freezer: freeze the cake whole or in slices, well wrapped, for up to 2 months. Defrost in the fridge overnight.
Ways to change it
- Mocha cake: dissolve 1 teaspoon of instant coffee in the tablespoon of water before you add it to the eggs.
- Chocolate orange: stir the finely grated zest of 1 orange into the batter.
- Cupcakes: bake the batter in 12 paper cases for 18 to 22 minutes and top each one with a spoonful of ganache.
- A different topping: swap the ganache for our tangy keto cream cheese icing.
Any of these changes will alter the nutrition figures, except the cupcakes, which match one slice each.
Nutrition
Per serving (1 slice, one twelfth of the cake, including the ganache):
| Nutrient | Per slice |
|---|---|
| Energy | 230 kcal |
| Fat | 21.7g |
| of which saturates | 11.6g |
| Carbohydrate | 16.4g |
| of which sugars | 0.7g |
| of which polyols | 14.6g |
| Net carbs | 1.8g |
| Fibre | 3.7g |
| Protein | 5.5g |
| Salt | 0.49g |
Net carbs are carbohydrate minus polyols. On UK labels, fibre is already listed separately from carbohydrate, so it isn't subtracted again. Figures are calculated from the Groovy Keto Chocolate Cake Mix and Dark Chocolate Buttons pack labels and UK (McCance and Widdowson's CoFID) data for the eggs (12-937), butter (17-661), double cream (12-334) and salt (17-367), and will vary with the brands you use. Excessive consumption of polyols, such as erythritol, may produce laxative effects.
Allergens: this recipe contains nuts (almonds), milk and eggs. The Chocolate Cake Mix pack says it contains almonds and milk, and that it is made in a facility where there may be traces of other nuts, cereals, milk and eggs. The Dark Chocolate Buttons pack says they are packed in a facility where there may be traces of nuts, cereals, milk and eggs. Always check the current pack labels before baking for anyone with an allergy.
FAQ
How many carbs are in a slice of keto chocolate cake?
Each slice of this keto chocolate fudge cake has 1.8g net carbs, worked out as 16.4g carbohydrate minus 14.6g polyols from the erythritol in the cake mix and chocolate. A slice is one twelfth of the cake, including the ganache, and also has 230 kcal, 3.7g fibre and 5.5g protein.
Can you freeze keto chocolate cake?
Yes. Once the ganache has set, freeze the cake whole or in slices, either wrapped well or in a freezer box with baking paper between the slices, for up to 2 months. Defrost it in the fridge overnight, then leave it at room temperature for 20 minutes so the ganache softens before serving.
What can I use instead of sugar in a chocolate cake?
A granulated erythritol sweetener, such as an erythritol and monk fruit decoction blend, is the usual swap, together with almond flour in place of wheat flour. Our Chocolate Cake Mix is already sweetened with erythritol and stevia, and so are the chocolate buttons, so you don't need to add any sugar or extra sweetener.
Is chocolate cake keto?
A traditional chocolate fudge cake isn't, because it's made with flour and sugar: a 62g slice of shop-bought fudge cake has about 34.5g carbohydrate, most of it sugars. This version uses a cake mix made with almond flour, coconut flour and cocoa, sweetened with erythritol and stevia, so each slice has 1.8g net carbs.
Why did my ganache split or go grainy?
Ganache usually splits when the cream is too hot or it's stirred too hard too soon. Heat the cream only until it steams, leave it on the chocolate for a minute, then stir gently from the middle. If it still looks oily, stir in a tablespoon of warm cream, a little at a time, until it comes back together.
Can I make this as keto chocolate cupcakes?
Yes. Line a 12-hole muffin tin with paper cases, divide the batter between them and bake for 18 to 22 minutes, as the cake mix pack suggests, until a knife comes out clean. Let them cool completely, then spoon a little ganache onto each one. The nutrition for each cupcake is the same as for one slice.
