Step 1

In a small bowl, combine the raisins with the rum and 2 tablespoons of hot water. Allow to soak at room temperature, stirring occasionally, until the raisins are plump and most of the liquid has been absorbed, at least 8 hours or overnight.

Step 2

In a stand mixer fitted with a paddle attachment, mix together the flour, sugar, yeast, salt, lemon zest and vanilla bean on low speed until combined. In a medium bowl, whisk together the eggs, tepid water and honey. With the mixer on low speed, pour the egg mixture into the flour mixture. Increase the speed to medium-low and mix until all of the ingredients are combined. Add the softened butter, 1 tablespoon at a time, mixing until incorporated before adding more. Increase the speed to medium-high and beat until the dough is smooth and elastic, about 8 minutes.

Step 3

Drain the raisins, discard the soaking liquid, and stir together with the candied citron and 1 tablespoon of melted butter. Stir this mixture into the dough with a wooden spoon.

Step 4

Place the dough in a large bowl, cover with plastic wrap, and let rise in a cold oven with the door closed until it has nearly tripled in volume, 12 to 15 hours.

Step 5

Locate and discard the vanilla bean, then sprinkle the dough lightly with flour and scrape out onto a lightly floured surface. Sprinkle a bit more flour onto the dough, then fold the edges of the dough in towards the center, forming a loose ball, and place, seam-side down, into the panettone mold. Cover with a damp kitchen towel (not terry cloth) and let rise in a draft-free place at warm room temperature until the dough is just above the top of the mold, 3 to 5 hours.

Step 6

Preheat oven to 370 degrees F.

Step 7

Place the dough-filled panettone mold on a baking sheet. Use a very sharp serrated knife to score an "X" across the entire surface of the dough. Place the 1 tablespoon chilled butter in the center of the X and bake until a wooden skewer inserted into the center comes out slightly moist but not wet, 60 to 75 minutes (the panettone will be very dark).

Step 8

Remove from the oven and pierce 12-inch metal or wooden skewers all the way through the panettone (including the paper) 4 inches apart and 1 inch from the bottom so the skewers are parallel. Hang the panettone upside down over a large stockpot and cool completely before cutting. To store the panettone, wrap tightly in plastic wrap, then either place in a resealable plastic bag, or wrap again in foil. The bread will keep at room temperature for up to 1 week. (I have not tried freezing the bread, but I believe it would freeze well, wrapped in plastic, then foil, then placed in a resealable bag.)