Mix buttermilk, yeast, 180gm bread flour together in your mixing bowl and set aside for 1 hour. The time will depend based on how warm your kitchen is. It might take 2 hours as well, we want the mixture to double in volume.
In the same bowl add the remaining 220gm bread flour and 3 whole eggs or 6 large egg yolks. Mix this together well. Ensure all the ingredients are well combined. This will take at least 5-8 mins in your stand mixer. Scrape down the mixture every now and then.
Add the sugar, salt, lemon zest, orange zest, vanilla paste, and mix well.
Add the butter into the dough slowly while mixing on low. Let the butter get incorporated into dough gradually. Once all the butter is added, mix the dough for 5 - 8 mins until smooth and silky.
Add the soaked dried fruit into the dough and mix on low. We don’t want the fruit to disintegrate so mix it gently until the dough has incorporated the fruit well. If the dough is not incorporating the fruit, stop the machine and let the dough relax for a few minutes before continuing.
Once all the fruit is encased in the dough let it rest for 2 hours covered at room temperature, we want this to double up in volume. It can take 1 hour or 4 hours, depending on the warmth of the kitchen.
After the dough is doubled, we spread out the dough on a clean kitchen surface and slowly stretch and fold the dough by folding all the corners into the center. Form a ball and cover on the counter and let it sit for 15 minutes. At this stage you can repeat this process 2-3 times to trap more air into the dough.
Transfer the dough into a panettone mould or a lined 9inch round tin that is brushed with butter and baking paper. Let this rise for 1-2 hours until doubled in size.
Brush the top of the panettone with egg wash and sprinkle over the pearl sugar, generously.
Preheat the oven to 170℃, this should be done for at least 20 minutes before baking. Bake the panettone for 15 minutes at 170℃ and reduce the heat to 150℃, bake it for 30-40 mins until the top is golden, the bread has risen. The internal temperature should be 79℃ (you can use a thermometer to make sure this is the case).
Once the panettone is baked pierce the bottom with a metal kebab skewer. And let the panettone hang upside down overnight to cool down completely. If you are baking it in a 9inch round tin, remove the panettone from the tin and then poke with the metal skewer and hang upside down, ideally with the baking paper.
After the panettone has cooled down, remove it from the baking paper and take out the skewers. Slice and serve with coffee and enjoy.