Preheat oven to 180 degrees Celsius (350 degrees Fahrenheit)
Place the coconut oil in a large bowl and melt over a saucepan of boiling water or in the microwave (skip this step if using any other oil)
Once melted, add the milk to the same bowl along with the vinegar, maple syrup, vanilla, salt and ground almonds
Sift in the flour, baking powder and bicarbonate of soda
Mix well, adding a tiny splash more milk if it’s looking too dry
Transfer mixture between two greased baking tins lined with baking paper (I used two 7inch/18cm springform baking tins)
Bake in oven for around 15 minutes until risen and an inserted skewer comes out clean
Once done, turn the cakes out onto wire racks and leave to cool completely before applying the custard
For the custard:
Heat up the milk in a saucepan with the maple syrup and vanilla
Dissolve the custard powder in a separate bowl in a little extra milk
Once the milk in the saucepan is steaming, add a little of the hot milk to the bowl with the dissolved custard powder, mix well and transfer the custard powder mixture to the saucepan
Mix well and keep stirring on a low heat for a few minutes until thickened. If it's looking too thick, add a little extra milk, and if it's looking too thin then add some more custard powder as required - in general, it's better for the custard to be too thick than too thin
Leave the custard to cool for around 30 minutes before applying to the cake - it doesn’t have to be completely cooled but it should have firmed up a little
For the chocolate ganache:
Melt the chocolate either over a bain-marie or in the microwave, add the milk and mix well
To assemble:
Place one half of the sponge on a cake stand or plate, and spread the custard evenly on top of it
Place the other half of the sponge on top of the custard
Pour the chocolate ganache over the top of the cake and spread evenly
I’d recommend keeping the cake in the fridge for a few hours until the chocolate ganache has set before cutting to avoid making too much of a mess
Tastes best when fresh, but keeps covered in the fridge for up to a few days
Notes
*You can alternatively use almond flour**If you'd like to keep the cake completely refined sugar free, you could buy a refined sugar free dark chocolate, or use my coconut oil-based chocolate sauce recipe here.