PREPARING THE STARTER:
In a small dish, combine the warm milk, sugar, and fresh yeast. Mix well until the yeast is completely dissolved. Gradually add the bread flour, mixing until the dough is smooth and uniform. Cover with plastic wrap and let it rise for about 15 minutes.

In a stand mixer, add the bread flour and all-purpose flour, 1 tablespoon of unsweetened cocoa powder, sugar, salt, egg yolks at room temperature, and warm milk. Mix for a few minutes until you have a smooth dough. Add the starter and continue mixing until it is fully incorporated, then turn off the mixer.

With the mixer off, add the vanilla extract, orange zest, lemon zest (I used only orange), and rum. Start mixing again. Once everything is well combined, begin adding the softened butter, cut into pieces (take the butter out of the fridge well in advance). Mix until all the butter is absorbed, adding one piece at a time.

This step will take some time, but don't rush. As soon as one piece of butter is absorbed, add the next, and continue until all the butter is incorporated. At some point, the dough will start to pull away from the sides and cling to the dough hook. At this point, add the chocolate chips along with 1 tablespoon of unsweetened cocoa powder. Mix well to combine, then add to the dough.

Continue mixing until the cocoa is fully incorporated and the chocolate chips are evenly distributed. Turn off the mixer, remove the dough hook, and transfer the dough to a low panettone mold (7 or 8 inches/18 or 20 cm). Brush the top of the panettone with melted butter, cover with plastic wrap, and let it rise in the oven (turned off) with a small pot of hot water until the dough is about 1/2 inch (1 cm) from the top (this will take about 2-3 hours).

After rising, remove the plastic wrap. Using a small knife, gently score a cross on top and lift the four corners slightly with the knife. Place a small piece of butter in the center and bake in the lower part of a preheated convection oven at 320°F (160°C) for 45-50 minutes, keeping the pot of hot water in the oven. When done, leave the oven door slightly open for 10 minutes.

Remove the panettone from the oven and insert two long skewers about 3/4 inch (2 cm) from the base. Turn the panettone upside down and let it cool (you can use a pot to support it) and cover with a cloth. Once cooled, remove the skewers and serve your panettone.
The original recipe also included a chocolate glaze, but I chose not to add it. Below are the ingredients for the chocolate glaze.

Ingredients for the chocolate glaze:
3 1/2 ounces dark chocolate (100 grams)
3 tablespoons butter (40 grams)
1 tablespoon rum

PREPARATION:
Melt the dark chocolate and butter together in a double boiler with 1 tablespoon of rum. Let the glaze cool slightly, then pour it over the panettone and decorate with chocolate shavings (1 1/2 ounces/40 grams)!