Pre-heat the oven to 175°C/350°F. Line a baking tray with baking parchment, leaving a 3cm overhang at the longest sides for easy removal from the tin later.
Sift together the flour, 180g caster sugar, potato starch and salt.
In a jug, whisk together the milk and apple cider vinegar. Set aside for 10 minutes. Once it looks like its curdled a little, add the vanilla extract and oil. Whisk briefly.
Pour the wet ingredients into the sifted dry ingredients and whisk until smooth, about 90 seconds. It should be of a flowing, ribbon consistency.
Immediately pour HALF of the batter into the lined tin and spread it out using a spatula. Rasp the tin on the counter top a dozen times to encourage any air bubbles to rise to the surface. This will give you a more even bake.
Bake the sponge in the preheated oven for 15 minutes. It should be springy to the touch and slightly golden on top.
Remove the sponge from the oven and allow to cool for 10 minutes. After this time, scatter 4 tbsp caster sugar over the top and give the pan a gentle shake to distribute it evenly. The surface of the sponge should look beautifully frosty. Carefully lift the sponge from the tin.
Repeat the same baking steps above to bake the second half of the batter.
Once both sponges have cooled, slice them into rectangles, about 2.5cm x 8.5cm. Carefully peel the sponge fingers away from the baking parchment and set them on a wire rack. Leave them out at room temperature, uncovered for 24 hours. Do not skip this step. The air-drying ensures the sponge fingers become dry enough to dip into the coffee without breaking.
To make the espresso:
Mix together the instant coffee and boiling water. Allow to cool completely. Now is the time to add any alcohol if you like. I kept mine alcohol free.
To make the mascarpone cream:
In a bowl, mix together the mascarpone and sweetened condensed milk. Once combined, whisk until smooth.
In a separate bowl, whisk the double cream until it produces soft peaks. Don't overwhip.
A little at a time, fold the whipped cream into the mascarpone mixture. The finished mascarpone cream should be smooth and able to hold a peak.
In a small bowl, mix together the cocoa powder and cinnamon.
To assemble to tiramisu:
Take a large glass or ceramic dish. Dip the now stale ladyfingers in the cold coffee until soaked, about 5-6 seconds and then arrange in the base of the dish. Top with 1/3 of the mascarpone cream and spread out into an even layer.
Use a tea strainer to sift half of the cocoa powder and cinnamon mixture on top of the mascarpone cream.
Repeat the sponge finger and espresso layering process. You can plug any gaps with broken sponge fingers to fit. Top with another 1/3 of the mascarpone cream.
Place the remaining mascarpone cream in a piping bag fitted with a large, round nozzle. Pipe little blobs of cream on the top of the tiramisu for a pretty finish. Sift the remaining cocoa powder and cinnamon mixture over the top of the tiramisu.
Cover the dish, taking care not to smudge the top. Refrigerate the tiramisu for at least 24 hours (or up to 72 hours) before serving.
Video
Notes
Since this tiramisu is eggless, it will keep well in the fridge for up to a week.
Freeze any leftover tiramisu in freezer-safe containers for up to 3 months. Defrost at room temperature and consume within 24 hours. Do not re-freeze.
If you don't want to pipe a design on top of the tiramisu, divide the mascarpone in half rather than thirds. Use half in the first layer and half on top.
Decaf coffee can be used in place of regular coffee.
Cinnamon is optional. Leave it out if you don't like it.
If you like your eggless tiramisu boozy, add 2-3 tablespoons of marsala, Bailey's, dark rum or whiskey to the cold espresso.
This recipe makes approx. 52 ladyfingers/sponge fingers.