Preheat oven to 150 degrees celsius (fan-forced). Grease and line a 20cm round cake tin with baking paper (on the base and sides) and set aside.
Place the butter, brown sugar, milk and white chocolate melts into a microwave-safe bowl and heat on 50% power for approximately 5 minutes or until melted (stirring every 30 seconds). Allow to cool slightly. Note: Alternatively, you can do this step in a saucepan on the stovetop.
Sift over the plain flour, self-raising flour and add the vanilla extract, eggs and salt. Mix together until smooth.
Pour the mixture into the prepared cake tin. Bake for 60 minutes or until a skewer inserted into the middle comes out with just a few crumbs on it. Allow the cake to cool before transferring to a wire rack or plate.
To make the caramel frosting, melt the butter in a microwave-safe bowl on 50% power.
Add the brown sugar and milk and stir together. Place back into the microwave for 2-3 30 second bursts or until slightly thickened. Allow to cool slightly for a few minutes.
Sift the icing sugar mixture over the top of the mixture and mix together with a whisk.
Spread the caramel frosting over the top of the caramel mud cake and serve.
Thermomix Method
Preheat oven to 150 degrees celsius (fan-forced). Grease and line a 20cm round cake tin with baking paper (on the base and sides) and set aside.
Place the butter, brown sugar, milk and white chocolate melts into the Thermomix bowl and melt for 4 minutes, 60 degrees, Speed 2 (or until melted and smooth).
Add the plain flour, self-raising flour and add the vanilla extract, eggs and salt and mix for 5 seconds, Speed 5. Scrape down the sides of the bowl and repeat for a further 5 seconds (or until smooth and combined). Pour the mixture into the prepared cake tin.
Bake for 60 minutes or until a skewer inserted into the middle comes out with just a few crumbs on it. Allow the cake to cool before transferring to a wire rack or plate.
To make the caramel frosting, place the butter, brown sugar and milk into the Thermomix bowl. Melt for 3 minutes, Speed 2, 60 degrees (or until slightly thickened. Allow to cool slightly.
Sift the icing sugar mixture into the bowl and mix for 5 seconds, Speed 5. Scrape down the sides of the bowl and repeat for a further 5 seconds.
Spread the caramel frosting over the top of the caramel mud cake and serve.
Video
Notes
RECIPE NOTES
Cover if browning - if the cake is browning too quickly, cover loosely with foil and continue baking.
Cool before frosting - allow the cake to cool completely, otherwise the frosting will melt and slide off.
Cut into small serves - this cake is rich and sweet; 16 slices is plenty!
Storage - store in an airtight container at room temperature for up to 7 days.
Freezing - wrap cooled cake (whole or sliced) in plastic wrap and foil, then freeze for up to 3 months. Defrost at room temperature.
Make ahead - bake and freeze the unfrosted cake, then add frosting before serving.
Decorating - this cake is firm and level, making it perfect for stacking or covering with fondant.