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Piece of white chocolate mud cake with white chocolate on top.
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White Chocolate Mud Cake

This white chocolate mud cake is moist and tender with a buttery white chocolate flavor. Topped with white chocolate ganache or white chocolate buttercream, it looks beautiful with a few raspberries. 
Course Dessert
Cuisine Australian
Keyword White Chocolate Mud Cake
Prep Time 30 minutes
Cook Time 1 hour 30 minutes
Cooling 4 hours
Total Time 6 hours
Servings 10 large pieces
Calories 652kcal

Equipment

  • 20-cm (8-inch) loose-bottom cake tin with 10-cm (4-inch) sides - see recipe notes for pan alternatives

Ingredients

White Chocolate Mud Cake

  • 170 grams unsalted butter (¾ cup)
  • 250 grams white chocolate (9 ounces) finely chopped
  • ½ cup hot water
  • 250 grams caster sugar (1 ¼ cups)
  • 250 grams all-purpose flour (2 cups) AKA plain flour
  • 2 teaspoons baking powder
  • ¼ teaspoon salt
  • 2 large eggs
  • 2 teaspoons vanilla extract
  • 180 ml sour cream - from the tub (¾ cup) I used 18% MF (light)

White Chocolate Ganache

  • 250 grams white chocolate (9 ounces) very finely chopped
  • 60 ml whipping cream (¼ cup)

White Chocolate Frosting

  • 250 grams white chocolate (9 ounces) finely chopped
  • 225 grams unsalted butter (1 cup) slightly softened
  • 3-4 cups icing sugar (about 330-440 grams)
  • ¼ teaspoon salt omit if using salted butter
  • 3-4 tablespoons milk (45-60 ml) or whipping cream

Instructions

White Chocolate Mud Cake

  • Preheat the oven to 150 C (300 F) on a fan-forced/convection oven. Or preheat to 160 C (325 F) on a standard oven.
  • Line the bottom and sides of a 20-cm (8-inch) loose-bottom cake tin with 10-cm (4-inch) sides.
  • Add the butter, chopped white chocolate and warm water to a large saucepan over low heat. Melt everything together while gently stirring.
  • Once smooth, remove from the heat and pour the mixture into a very large bowl. Set aside to cool.
  • In a separate large bowl, whisk together the sugar, flour, baking powder and salt.
  • Once the butter and chocolate mixture is no longer hot (it can still be warm), whisk in the eggs and vanilla extract. Then whisk in the sour cream until there are no lumps.
  • Working about ½ at a time, whisk the flour mixture into the liquid ingredients until smooth.
  • Pour the batter into the prepared pan.
  • Bake in the preheated oven for about 90 minutes for a 20-cm pan, or 75 minutes for a 23-cm tin. When the cake is done baking, an inserted toothpick should come out clean or with a few crumbs clinging to it. If you gently press down on the top of your cake with your finger, it shouldn't really give. If you're in doubt, it's better to bake for another 5-10 minutes - this cake is very unlikely to go dry.
  • Remove from the oven and cool fully before adding frosting or ganache
  • Invert the cooled cake onto a wire rack. If the top is rounded, optionally use a serrated knife to gently saw off the domed top. Only do this once the cake is 100% cooled.

White Chocolate Ganache

  • Add the finely chopped white chocolate to a medium-sized heatproof bowl.
  • Heat the cream until very hot (but not boiling). Pour the hot cream over the chopped chocolate and let sit for 2-5 minutes.
  • Whisk until smooth. You'll first need to whisk slowly so that the cream doesn't spill, then whisk more vigorously as the ingredients start to combine. If the chocolate hasn't quite fully melted, microwave on medium power for 30 seconds and whisk until smooth.
  • Place the ganache in the fridge for 30 minutes. Then spread the cooled ganache over the top of the cake.

White Chocolate Buttercream

  • Place the finely chopped chocolate in a heatproof bowl and microwave for 30-second intervals on low-medium power (I typically use 180 or 360 watts). Stir between each interval until smooth. Set aside.
  • In a very large bowl, beat the butter until fluffy.
  • Mix in 2 cups powdered sugar and the salt.
  • Ensure that the melted white chocolate is room temperature. Then beat it into the butter mixture.
  • Beat in the rest of the powdered sugar about ½ cup at a time, alternating with a tablespoon of milk (or cream) until the desired sweetness and thickness is reached.
  • For a singly layer cake, place the cooled cake on the plate that you plan to serve it and frost the top and sides with swirls of frosting.
  • For a double layer cake, place one cake layer on the plate you plan to serve it on (place the serrated side down) and frost the top with a layer of frosting. Place the second cake layer on top (again - serrated side down) and frost the top. Optionally, frost the sides of the cake too.

Notes

  1. Cake Tin Sizes: This cake can also be made in a 23-cm (9-inch) pan with 5-cm (2.5 inch) sides. I definitely prefer to use a loose-bottom pan. For a 23-cm pan, the bake time will be around 75 minutes at 150 C (300F) in a fan-forced oven, or 160 C (325 F) in a standard oven. 
  2. For a Double Layer Cake: Bake as directed in the recipe using one 20-cm or 23-cm tin. Once the cake has fully cooled, slice the cake layer in half. Alternatively, bake the cake in two 20-cm or 23-cm cake tins (ensure they have sides at least 5 cm tall for a 20-cm tin). The bake time will be about 30-40 minutes at the same temperature.
  3. Butter: If using salted butter, omit the salt from the recipe.
  4. Frosting vs Ganache: You do not need to make both the ganache and frosting - I've included both so you have options. 
  5. Ganache: The ganache is enough for a thick layer on top of a single layer cake, or a thin layer in the middle and on top of a double layer cake. Double the recipe for a thick layer in the middle and on top of a double layer cake. If making a layered cake, after adding ganache on top of the first layer, place it in the fridge for about 30 minutes for the ganache to firm up before adding the top layer.
  6. Frosting: The frosting is enough for a thick layer on the sides and top of a single layer cake, or a thin layer in the middle, sides and top of a double layer cake. If you only want a layer on top of a single layer cake, divide the frosting recipe by 2.
  7. Storage: Store cake covered or in an airtight container at room temperature for up to 2 days (as long as your kitchen isn't warm). Or store covered in the fridge for up to 4 days. Remove the cake from the fridge and let it sit at room temperature for about 30 minutes before enjoying.
  8. Nutrition: Nutrition information is an estimate only and based on 1 slice with chocolate ganache (not frosting), assuming that the cake is sliced into 10 equal pieces. 

Nutrition

Calories: 652kcal | Carbohydrates: 75g | Protein: 7g | Fat: 37g | Saturated Fat: 22g | Polyunsaturated Fat: 2g | Monounsaturated Fat: 10g | Trans Fat: 1g | Cholesterol: 102mg | Sodium: 137mg | Potassium: 300mg | Fiber: 1g | Sugar: 55g | Vitamin A: 694IU | Vitamin C: 1mg | Calcium: 172mg | Iron: 2mg