Make the starter by mixing together the flour, sugar and yeast, then pour over room temperature or slightly warm plant milk and work with a fork until all is well combined. Cover the yeast mix, and place in a warm place until it triples its size (it will take around 1:30h at ideally 26°C).
Meanwhile place the vegan butter block at room temperature.
Once the yeast mix has risen it is time to start adding the ingredients of the first dough. Add first the sugar, then room temperature or slightly warm plant milk, and finally the flour. Work the dough for a few minutes until the ingredients come nicely together (you can also use a dough mixer if that's easier or you're making more batches), then cover again and put it back for the second proof until it doubles its size (1:30-2 hours, depending on house temperature).
Dissolve some turmeric or yellow food coloring into the plant milk (I add a pinch of coloring until the milk turns bright golden). As per the first dough, work the remaining ingredients into the dough starting from the sugar, then the milk, the salt, the zests and vanilla, and finally the flour, until the mixture no longer sticks to the sides of the bowl. Cover again and proof for 2-3 hours.
For the lamination step roll the risen dough into a rectangle shape onto a lightly floured surface. Spread the plant butter on the central portion of the dough and fold each side over half of the buttered portion. Now fold the upper and lower sides, one onto the other, wrap with film and place in the fridge for half an hour.
After 30 minutes roll the folded dough again and repeat the folds. Place back into the fridge for 15 minutes.
Repeat the folding (step 6) 2 more times, then shape the dough into a ball.
Generously butter the pandoro mould and sprinkle it with some flour. This will prevent the pandoro sticking to the mold.
Carefully place the dough in the mold with the smoother side of the ball down. Cover with plastic film and a table cloth and allow to rest in the fridge overnight.
The morning after remove from the fridge and leave in a warm environment to rise for 6-7 hours, or until the dough reaches the top of the mold (once again, the recommended temperature is 26°C. The oven with the light switched on works perfectly).
Preheat the oven at 180°C and bake the pandoro for 20 minutes. After the first 10 minutes cover it with a foil sheet to prevent the bottom from burning. Lower the oven heat to 160° and cook for another 50 minutes.
Allow the pandoro to cool down completely at room temperature before removing it from the mold.
Before serving, sprinkle the Pandoro with abundant icing sugar.