Chocolate layer cake with peanut butter frosting

This show-stopper chocolate cake can be prepared a day in advance although you may need to remove a shelf from your refrigerator to make enough room!

Chocolate layer cake with peanut butter frosting Credit: Chris Middleton

• serves

  20

• prep

  2 hours

• cook

  1 hour

• difficulty

  Ace

Make the cake, layer, frost and drizzle with chocolate, then chill until about one hour before serving for the frosting to come back to room temperature. You can make the peanut brittle in advance (just make sure you store it in an airtight container), but don’t add it to the cake until ready to serve.

Ingredients

• 2 quantities everyday chocolate cake, omitting the icing
• 2 tbsp roasted black sesame seeds
• handful freshly popped popcorn

Peanut butter frosting

• 375 g (13 oz) butter, softened
• 420 g (15 oz/1½ cups) natural smooth peanut butter
• 120 g (4 oz/¾ cup) dextrose
• 100 g (3½ oz) sour cream

Peanut brittle

• 240 g (8½ oz/1½ cups) dextrose
• 1 tbsp glucose syrup
• 75 g (2¾ oz) butter, chopped
• ½ tsp bicarbonate of soda (baking soda)
• 150 g (5½ oz/1 cup) roasted salted peanuts

Chocolate drizzle

• 100 g (3½ oz) dark chocolate (70–85% cocoa solids), roughly chopped
• 100 g (3½ oz) butter, chopped
• 2 tsp glucose syrup

Chilling time: 1 hour

Instructions

Make the chocolate cakes, omitting the icing. You will need four layers of cake for this recipe.

To make the peanut brittle, line two large baking trays with non-stick baking paper. Put the dextrose, glucose syrup and 80 ml (2½ fl oz/⅓ cup) water in a large saucepan over medium-high heat. Cook, gently swirling occasionally until the glucose has dissolved. Bring to the boil and cook, without stirring, until you have a golden caramel, about 10 minutes. Remove from the heat and add the butter gradually, whisking well between each addition, until combined. Stir in the bicarbonate of soda, taking care as the mixture will bubble up slightly. Working quickly, stir in the peanuts and pour the mixture over one of the prepared trays. Place another piece of baking paper on top and use a rolling pin to flatten the mixture as much as possible. When the caramel is cool enough to handle, after about 5 minutes, stretch sections of the mixture, starting from the edges, to create interesting shapes. Set aside to cool. Snap larger sections into shards. Any leftovers can be stored in an airtight container for up to a week.

Make the peanut butter frosting. Beat the butter and peanut butter in a large bowl with an electric mixer, until light and fluffy. Add the dextrose gradually, beating well between each addition. Add the sour cream and beat until combined. Refrigerate to keep cool if the room temperature is warm.

If the cakes are domed, trim the tops off to level them with a serrated knife. 

Put a little dollop of frosting in the centre of a serving plate and place four strips of baking paper around the

edge. This will help to keep the plate clean of any icing. Place one layer of cake on the prepared plate. Spread about 80 g (2¾ oz/½ cup) of the frosting over the cake, taking it just over the edges. Repeat with the remaining three layers, placing the top layer of the cake bottom side up (to achieve a sharp edge). Spread a little more frosting thinly over the top and side of the cake. Scrape off any excess frosting and discard it (especially if it contains crumbs). This is called the ‘crumb coat’ and will keep the final layer of icing crumb-free. Put the cake in the refrigerator for the frosting to firm up, about 30 minutes.

For the final layer of icing, spread the top and side of the cake generously with the remaining frosting, smoothing the side with a long spatula. Using a gentle throwing action, throw pinches of the sesame seeds at the base of the cake. Most of it should stick! Put the cake back in the refrigerator for the icing to firm, about 30 minutes. 

To make the chocolate drizzle, combine the chocolate, butter and glucose syrup in a heatproof bowl and melt over a saucepan of simmering water. Stir until combined. Remove from the heat and set aside to cool to almost room temperature. The mixture needs to be runny enough to pour, but not so warm that it will melt the frosting on the cake. Working quickly, pour the chocolate onto the top of the cake and use an offset spatula to spread it evenly over the top, allowing the mixture to drip down the sides. Just before serving, decorate the top of the cake with the shards of peanut brittle and the popcorn.

The undecorated cake can be made a day in advance and stored in the refrigerator. Once decorated, it is best eaten straight away. The cake is best served at room temperature; otherwise the frosting will be very firm.

This recipe is from Incredible Bakes (Smith Street Books). Photography by Chris Middleton. 

Cook's Notes

Oven temperatures are for conventional; if using fan-forced (convection), reduce the temperature by 20˚C. | We use Australian tablespoons and cups: 1 teaspoon equals 5 ml; 1 tablespoon equals 20 ml; 1 cup equals 250 ml. | All herbs are fresh (unless specified) and cups are lightly packed. | All vegetables are medium size and peeled, unless specified. | All eggs are 55-60 g, unless specified.

Make the cake, layer, frost and drizzle with chocolate, then chill until about one hour before serving for the frosting to come back to room temperature. You can make the peanut brittle in advance (just make sure you store it in an airtight container), but don’t add it to the cake until ready to serve.