Pour brewed coffee and sifted cocoa powder into a small pan and stir until smooth and combined. Bring to a boil over medium heat, stirring constantly. Take off the heat and leave until completely cooled.
Add the caster sugar, salt, baking powder and bicarbonate of soda to a large bowl and whisk until combined. Beat in the eggs one at a time until fully incorporated.
Pour in vegetable oil, orange juice and orange zest and mix.
Next, beat in the cooled coffee and cocoa mixture which will now be thicker.
Sift over the flour and beat until combined before finally mixing in the buttermilk.
Pour into a bundt tin that has been greased with butter and lined with a layer of cocoa powder, this will make it easier to take the cake out later.
Bake in a preheated oven at 180ºC for 60 minutes. Once baked, leave to cool completely in the tin.
Gently heat the double cream, in a small pan over a medium heat, until it just comes to the boil. Pour half over the white chocolate and half over the milk chocolate. Leave to sit for 20-30 seconds before stirring. If you prefer a thicker ganache drip you might not need to add all the cream.
If the chocolate hasn’t completely melted pop it in the microwave to finish off the melting.
Turn out your bundt cake onto your serving plate before drizzling the two ganaches over to create a marble effect. Use a skewer to create a better effect.