This is a delicious confection of moist chocolate sponge, light and fluffy Seville orange curd Swiss buttercream, and a luscious orange chocolate glaze. At other times of the year, this would be just as good made with regular oranges.
For the cake (Recipe adapted from www.callmecupcake.se)
75g unsalted butter, melted and cooled
270g plain flour
60g cocoa powder
1 ½ tsp baking powder
1 ½ tsp bicarbonate of soda
360g golden caster sugar
2 medium eggs
225ml whole milk
150ml boiling water
Preheat your oven to 170c (160 fan). Butter and line the bases of two 15cm cake tins with baking parchment.
Place all the ingredients in a large bowl and beat until a smooth batter is formed. Divide the batter equally between the two tins and bake for 30-40 minutes, until a cake tester or skewer comes out almost clean, with just a few moist crumbs. Cool the cakes in the tins for 10 minutes and then turn out to cool completely.
For the Seville Orange Curd Swiss Meringue Buttercream
Whites from 4 large eggs
250g caster sugar
250g unsalted butter, at room temperature
3 tablespoons Seville orange curd (See below)
Small amount of orange gel colour (optional)
Place the egg whites and sugar in a bowl over a pan of simmering water and whisk until the mix reaches 65 C and all the sugar has dissolved. Take the bowl off the heat and continue whisking until a soft peak meringue is formed and the bowl is completely cool. Add the butter gradually and beat for another few minutes, until smooth, but be careful not to overbeat. Add the Seville orange curd and beat again briefly until smooth. Left as it is, the buttercream will be a creamy white with subtle orange flecks- very pretty, but if you prefer you can also add a little paste or gel colouring as I have here, to make it a stronger orange colour.
(If you are not using the buttercream straight away leave it in the bowl at room temperature with cling film directly over the surface- it will sit quite happily like this for at least a day. You may need to whip it slightly to resoften before use.)
For the Seville orange curd
Makes one large jar, so you will have some spare from the cake to eat on toast, crumpets or with a spoon!
6 Seville oranges – you need the juice of all 6 and the finely grated zest of 1
2 large eggs, lightly beaten
110g caster sugar
110g unsalted butter, at room temperature.
Wash a large jam jar and lid with hot soapy water and then sterilize by placing in a hot oven for a few minutes.
Place all the ingredients in a small pan over a low heat and stir until they are melted together. Continue to heat, stirring, until the curd thickens and coats the back of a spoon. Remove from the heat and allow to cool slightly, then pour into the sterilized jar.
The curd will keep in the fridge for at least a week.
For the chocolate glaze (recipe adapted from Martha Stewart Living)
NB make the glaze while the frosted cake is chilling (see below) or it may set before you want to use it!
300ml of double cream
1 tbspn light corn syrup or golden syrup
Pinch of salt,
285gm chocolate- I used 100gm dark chocolate, 100g milk and 85g dark orange, for a semi-sweet flavour with a hint of orange, but you can adapt this as you wish- don't make it too bitter though!
Place the cream, corn or golden syrup and salt in a pan and bring just to the boil. Take off the heat, add the chocolate and leave for 5 minutes to allow the chocolate to melt, and then beat until smooth. Leave to cool completely.
To assemble the cake
Using a serrated knife, level the tops of your two chocolate cakes and slice each into two horizontally. Place a 15cm cake board (or a circle of clean cardboard 15cm in diameter) on a turntable, and top with the first cake slice. (You may find it useful to use a larger flat round surface such as the base of a tart tin between the cake board and turntable for ease of working and of moving the cake.)
Spread the top of the first cake slice with a small amount of Seville orange curd, and then a thicker layer of the buttercream (small offset spatulas will be useful for this if you have them). Top with the second cake slice, and then repeat the filling and layering until all four cake slices are stacked.
Cover the entire cake with a thin 'crumb coat' of buttercream and place in the fridge to set for about 15 minutes. Then, using a spatula cover the entire cake with a generous smooth layer of buttercream. I've also used a cake scraper on the sides of the cake, but you can get a good finish using just a spatula.
Place the cake back in the fridge to set fully- at least an hour.
While the cake is chilling, make the chocolate glaze and let it cool to room temperature. Once the cake is chilled, add spoonfuls of the glaze to the top of the cake and use a spatula to push drips and rivulets over the sides. Give the top of the cake a final smooth and then leave for the glaze to set.
The cake will look lovely just with the glaze, but if you wish you can also use a piping bag with a star nozzle fitted to add buttercream rosettes to the top, as a finishing touch. I've added a subtle further dimension of colour by using a new clean paintbrush to paint stripes of orange gel colour up the inside of the nozzle and bag before adding the buttercream. This will give you subtly striped rosettes!
This cake should keep for 2-3 days at room temperature.