1) Biga: Combine the flour, water and yeast, kneading briefly to make a stiff dough; if you're using a bread machine, allow the dough to knead for 5 minutes, then cancel the machine.
2) Place the dough in a lightly greased bowl, and allow it to rise overnight, about 12 hours. It'll become bubbly.
3) Dough: In the bowl of an electric mixer (or in the pan of your bread machine), combine all of the ingredients except the dried fruit. Note: This dough is very difficult to make by hand; we suggest the use of a machine of some sort.
4) Knead the dough till it's cohesive; it'll seem very gummy at first, but should come together nicely at the end. Don't worry if it doesn't form a smooth ball; it's OK if it sticks to the sides of the bowl a bit.
5) Place the dough in a lightly greased bowl, and allow it to rest for an hour. It won't rise much; that's OK.
6) Knead the fruit into the dough, by hand or machine; knead only until the dough accepts the fruit, as over handling will cause the fruit to release too much sugar into the dough, slowing the rise.
7) Allow the dough to rest for 10 minutes, then shape it into a round ball.
8) Poke a hole in the center of the ball.
9) Slip the dough over the ring of a lightly greased 9" to 10" tube pan or monkey bread pan.
10) Cover the pan, and set the dough aside to rise for 2 hours or so. It probably won't double in size, but will puff up a bit; don't worry, this bread's oven spring is quite good.
11) Bake the panettone in a preheated 350°F oven for 25 to 40 minutes, tenting it with aluminum foil for the final 15 minutes of baking if it appears to be browning too quickly. There's a wide time-range here due to the difference in center diameters of monkey bread and tube pans; the smaller the diameter, the longer the bread will bake. The internal temperature of the dough should register 190°F to 205°F when it's done, so use an instant-read thermometer to check. If you don't have a thermometer, poke a cake tester into the center; it should come out dry, without any crumbs or wet dough clinging to it.
12) Remove the panettone from the oven, and after about 5 minutes turn it out of the pan. Brush with melted butter, if desired, for a soft, buttery crust. Ccool on a rack.
13) Sprinkle with confectioners' sugar just before serving, if desired.