Next, sift in the plain flour & cocoa powder, and whisk it in carefully until it is fully incorporated. 

Finally, pour in the vegetable oil and whole milk whisk this in, making sure to scrape the bottom of the bowl as the oil can sink to the bottom if you don’t incorporate it correctly.

Pour half of the batter onto the lined tray, and then using a spatula, spread the batter out evenly. Try to ensure the batter is as even as possible. If using a silicon sponge roll mat, use a ruler to level the batter completely with the edge of the mat.

Bake the sponge for 12-14 minutes, then allow to cool for 5 minutes, before flipping it onto a sheet of parchment paper. Bake the second sponge using the remaining batter, using a whisk just to briefly whisk the batter together again before pouring it onto your tray.

They don’t need long to cool as they are quite thin, so it is best to bake these fresh, just before the cremeux has finished chilling (about an hour before).

Into a small bowl, add the powdered gelatin and cold water. Stir it together then allow it to bloom for 10 minutes. It should absorb all the liquid, and dry out slightly.

Once set, scoop this into a tall jug, along with the nappage or apricot jam (if you are using apricot jam, ensure it is smooth, with no lumps of fruit)

Add the cream and water to a small saucepan, and heat it over a medium heat just for around 30 seconds, stirring occasionally.

Tip in the sugar and cocoa powder, then whisk it together, until it reaches a boil. Cook it for 30 seconds, then remove it from the heat and pour it over the gelatin/nappage mix.

Blend it with a hand blender until smooth, trying as best as possible not to incorporate lots of air bubbles.

The glaze needs to cool to 25-27C (77-80F) before it is ready to use. This takes roughly 1-2 hours at room temperature. So it is best to make this just after the first sponge goes in the oven. You can also make this ahead of time and store it in the fridge. It will set completely, but you can simply melt it in brief bursts in the microwave and blend again till smooth, then cool to the desired temperature. 

Take one of the cooled sponges, and scoop half of the cremeux onto it. Use a palette knife (or even better a raplette) and spread it out as evenly as possible so that you have a relatively thin, but even layer. If you find the cremeux is a little stiff to spread, simply heat your spatula under some hot water then dry it off. 

Repeat this with the second sponge. You may have a little spare cremeux depending on how thin you spread the cremeux. 

Using a sharp knife, cut the each sponge into 4 equal rectangles. Repeat this with the second sponge. You should have a total of 8 rectangles. 

Line a tray with a silicon mat or a sheet of parchment paper and carefully stack the sponges on top of each other. The sponge is flexible, but delicate so don’t be careless as you move them around or they will rip. Work quickly but carefully!

Stack all the sponges on top of each other, ensuring the very top layer has the cremeux facing up. Don’t worry about the stack looking rough and a bit wonky. We will trim off all the edges. Place the cake into the freezer for 20 minutes.

While it is freezing, this is where you need to ensure your mirror glaze is nearly at temperature. You can keep the cake in the freezer for longer if your mirror glaze isn’t quite ready, but just remember it will need longer at room temperature before you can serve it.

Once the cake has chilled and the glaze it at the correct temperature, carefully lift the cake onto a wire rack and pour the glaze over the top, letting it drip down the sides. You might not quite need all of the glaze. Just use enough to cover the top of the cake. Let it set for 2-3 minutes.

Then, using a hot and very sharp knife, cut all the rough edges off of the cake, you should be left with a neat, small rectangle.

Cut the remaining cake into 4 equal slices, I prefer long rectangular shapes but really you can cut any shape or leave it whole. The thin slices can be a little unstable as the cake is so tall!

It can be served immediately so that the cremeux is still nice and soft. If it has been frozen for longer, then it will need more time at room temperature until that creemux is soft.