Benjamina Ebuehi’s Chocolate Buttermilk Traybake with Muscovado Frosting and Thyme Caramel

Preheat the oven to 180ºC (160ºC fan/ 350ºF/gas mark 4). Grease a 23 x 33-cm (9 x 13-in) round cake pan and line with baking paper, leaving enough overhang to help you pull it out later.

Add the butter and chocolate to a heatproof bowl and melt in short bursts in the microwave or set over a pan of simmering water. Set aside to cool a little.

Mix the buttermilk and eggs together in a small jug (pitcher) and set aside.

Add the flour, sugar, cocoa powder, baking powder, bicarbonate of soda and salt to a bowl and mix to combine. Make a well in the centre and pour in the buttermilk mixture followed by the melted chocolate. Give it a good mix until you have a smooth, thick batter. Pour in the hot water and gently stir to combine.

Pour the batter into the prepared cake pan and bake for 40–45 minutes or until a skewer inserted into the middle comes out clean. Set aside to cool completely in the pan.

To make the caramel, add the cream and thyme to a small saucepan and heat gently until warmed through. Remove from the heat and cover to let it infuse for at least 20 minutes, although an hour is preferred.

Strain the cream and set it aside. Clean your saucepan and add in the sugar. Heat gently until the sugar melts and turns a deep amber colour. Give the pan a swirl every now and then to help it melt evenly.

Add in the butter – the sugar will spit and bubble so be careful – and mix quickly to combine. Slowly pour in the cream while stirring, and then let the caramel bubble away for 30 seconds. Remove from the heat and add the salt. Let it cool completely.

To make the Swiss meringue buttercream, add the egg whites and sugar to the bowl of a stand mixer. Place the bowl over a pan of simmering water, making sure the bottom of the bowl isn’t touching the water.

Keep the water at a simmer while whisking the egg whites. Once the sugar has dissolved and the egg whites are hot to the touch, remove from the heat. Whisk the whites on high speed until they are thick and glossy and the bowl is cool to touch.

With the mixer still running, add in all the softened butter and salt. The mixture will deflate and look a bit curdled but as you keep whisking it will come together. If after 5 minutes the buttercream looks really soupy, stick it in the fridge for 20 minutes and then continue to whip. Once the buttercream is smooth and silky, mix on low speed for about a minute to remove any large air bubbles.

To assemble, spoon the buttercream onto the cake, adding some swirls and swoops with a palette knife or the back of a spoon. Drizzle some caramel on top and decorate with a few sprigs of thyme.