Line the bottom of the mold with parchment paper. There's no need to line the sides unless you don't have a cake knife for easy removal. Preheat the oven to 180°C.
Combine the butter and milk in a bowl, then place the bowl in hot water (hot water bath). Once the butter has melted, leave the mixture in the bowl as is. Sift the cake flour and set aside.
Add the soft light brown sugar to the eggs, and then add to the mix in the hot water bath. Whisk until the batter is pale and thick (the photo is still in the progress).
Remove the mix from the hot water bath halfway through and continue to whip. Continue until the batter reaches ribbon stage. In the final stage, mix at low speed to allow the batter to form the desired consistency.
Next add in the vanilla oil, sift in the cake flour once more, and gently mix by scooping the batter up from the bottom and turning over.
Add two ladles of the batter from Step 5 into the dissolved butter and milk from Step 2, blend together, and mix it back into the Step 5 mixture (this method is foolproof).
Gently mix, and pour into the mold. Rap the pan against your work surface to remove any air bubbles, and lightly mist with water. Set the oven to 180°C for 25 minutes and bake.
This is about 8 minutes into the baking. This is as much as it will rise up. Once it turns golden brown cover with aluminium foil, reduce to 170°C, and bake for the remaining 17 minutes.
It is done once a wooden skewer inserted into the cake comes out clean. Drop the cake from small height to prevent shrinking.
It is ok to remove it from the mold straight away. Cover in plastic wrap and let sit for a day to let the flavours meld. You can slice it into 3 layers.
Use 3 eggs, 85 g cake flour, 80 g light brown sugar, 20 g butter, and 30 g milk to make an 18 cm version of this cake.
This is a decorated version of the cake that I made for my eldest son's 15th birthday Bisque Cake Recipe ID: 705870.
This is the cake I made for my second son's 13th birthday.
Story Behind this Recipe
I bake this every year for Christmas and birthdays, but a 18 cm pan wasn't big enough, so I tried baking in a 21 cm pan.
I wrote in Step 5 how to mix in the butter and milk into the batter, but if you've followed the recipe exactly, you can add it directly to Step 4. However, there's a high possibility that the batter would sink, so it's best to keep the two steps separate.