The showstopper challenge on the mighty caramel week for the GBBO 2017 series was all about making an impressive caramel cake. As my partner's family is Polish, I've been keeping an eye on Julia's bakes, as she keeps making eastern European inspired bakes. I was really intrigued by the cake she made this week, a light poppy seed cake with a walnut and prune filling and caramel frosting, so thought it'd be fun to give it a go.
The cake was a big success! The cake was really lovely and airy, but still had a lot of flavour, and the filling was a bit hit with my boyfriend's mum :) I altered the caramel sauce and buttercream a little - I wanted the buttercream not quite as sweet, so used treacle instead of the golden syrup Julia used. otherwise this recipe doesn't stray too far from what was seen on the show. I had some fun with the caramel decorations though - they aren't as difficult as you might think! Just be very careful, boiling caramel really hurts :(
Makes one 20cm cake (easily feeds 12)
Ingredients:
For the sponges:
- 200g (7/8 cup) unsalted butter/margarine
- 5 medium eggs, at room temperature
- 200g (1 cup) caster sugar
- 1½ teaspoons vanilla extract
- 10g (2 tsp) poppy seeds
- 200g (1 & 3/4 cups) self-raising flour, sifted
For the filling:
- 75g (1/2 cup) walnut halves or pieces
- 75g (1/2 cup) semi-dried prunes (I used Whitworths, which are partially rehydrated)
For the caramel sauce:
- 50g (1/4 cup) butter or margarine
- 100g (1/4 cup + 2 tsp) treacle
- 150g (2/3 cup) caster sugar
- 150ml (3/5 cup) double cream
For the buttercream:
- 50g (1/4 cup) softened butter
- 50g (1/2 cup) icing sugar, sifted
For the caramel decoration:
- 240g (2 & 2/5 cups) caster sugar
- 4 tablespoons water
- 9 walnut halves
Method:
1. Preheat the oven to 190°C (170C fan)/375°F/Gas mark 5. Grease the base and sides of two loose-bottomed 20cm cake tins, and dust lightly with flour.
2. Gently melt the butter/margarine (in a microwave or in a saucepan) and leave to cool until needed.
3. Separate the eggs, placing the egg whites into a large grease-free bowl, and the yolks into a another large mixing bowl. Whisk using a hand-held electric whisk (or use the whisk attachment of a stand mixer) until the whites stand in soft peaks when the whisk is lifted from the bowl. Whisk in 100g of the caster sugar to make a stiff, glossy meringue. Set aside.
4. Add the remaining 100g of sugar to the yolks, along with the vanilla extract, and whisk (there’s no need to wash the whisk) until very thick and mousse-like and the whisk leaves a distinct, ribbon-like trail when lifted from the bowl. Whisk in the poppy seeds.
5. Using a large metal spoon or similar implement (I used a metal palette knife), carefully fold in a third of the sifted flour. Once you can't see any speckles of flour, add a third of the eggs whites, and fold in. Repeat this, alternating between adding flour and egg whites, until it has all been incorporated.
6. Pour the melted butter/margarine around the sides of the bowl and gently (but thoroughly) fold in. Divide evenly between the two cake tins.
7. Bake the sponges for about 18-20 minutes until golden, well risen and starting to shrink away from the sides of the tin - if you press the centre of the sponge it will spring back. Leave to cool for 5 minutes in their tins, then turn out onto a wire rack to cool completely.
8. For the walnut and prune filling, roast the walnuts in the preheated oven for around 10 minutes, stirring after 5 minutes, until they smell nutty and are golden in colour. Leave to cool. Put the prunes into the bowl of a food processor and blitz to make a thick puree. Scrape down the sides of the bowl, add the walnut and blitz the pieces (briefly) until they are chopped medium-fine. Transfer to a bowl and set aside.
9. To make the caramel sauce to flavour the filling and buttercream: place the butter, treacle and caster sugar into a medium pan and stir over a low heat until melted and smooth. Meanwhile heat the cream in another pan until it is just simmering.
10. Bring the sugar/treacle mixture to the boil and cook for about 4 minutes, or until becomes thicker and even darker in colour. Stir the mixture often to ensure it doesn't burn. Remove the pan from the heat, cover your hand with an oven glove and very carefully add the hot cream.
11. When the foaming subsides, return the pan to a low heat and whisk constantly with a wire hand whisk for a few minutes until thickened (on a sugar thermometer the temperature would read 110C/230F). Pour into a heatproof bowl. Leave to cool to room temperature, then place in the fridge to chill fully.
12. For the caramel buttercream: beat the butter/margarine until it is very smooth and fluffy. , until very light in colour and texture. Gradually whisk in the caramel sauce. When it’s very smooth and light, remove 100g and mix this into the prune/walnut filling.
13. Add the sifted icing sugar and beat until it is smooth but not too slack - if it seems very loose, add more icing sugar. Transfer ⅓ to a separate bowl for the ‘crumb coat’.
14. To assemble the cake, level both sponges, then set one sponge top-side down on a serving plate. Spread with the walnut/prune filling. Place the second sponge on top.
15. Evenly spread the top and sides of the cake with the buttercream set aside for the ‘crumb coat', using a palette knife or spatula. Chill for 10 minutes, or until it is no longer sticky to the touch. Using a cleaned palette knife or spatula, neatly spread the remaining ⅔ of caramel buttercream over the entire cake and chill until firm.
16. Meanwhile, make the caramel for the shards: put the sugar into a medium pan and shake the pan so it settles in an even layer. Add the water, and place on a low heat. Gently melt the sugar, tilting the pan occasionally until the sugar has dissolved. Meanwhile grease and line the base of a baking tray with baking parchment.
17. Once all of the sugar has melted, turn up the heat and boil without stirring until the syrup turns a rich, golden-brown caramel colour. Take off the heat, and leave until cool (to speed up this process you can dip the pan in some cold water/ice). Once the caramel is thick enough to leave a trail from the pan, use a whisk to spread the caramel out on the baking parchment - make a thick line about 7cm in size at the bottom, then have fun drizzling the caramel above this (this will make a feature for the cake that should have stability due to this base). If the caramel gets too thick, place back on a low heat for a few minutes.
Reserve 1/4 of the caramel for the walnuts.
There are other fun things you can do with the caramel. For example, to make a sugar cage, grease a ladle and drizzle the caramel over in a web pattern. Whilst warm (but not too hot), gently peel the cage away. If it gets too cold, I found out (to my horror) the caramel sticks to the spoon...
18. Place the walnut halves in the reserved caramel and swirl to get an even coating (I'll admit, mine weren't as even as I'd like - we can always improve!), then tip out to cool. Leave to set.
19. Once the caramel is hard, press the large into the buttercream on the top of the cake and decorate the top with the caramel coated walnuts.