Sprinkle the yeast over the warm water in a medium bowl. Stir a few times and let stand to allow the yeast to dissolve and begin bubbling, 1 to 2 minutes. Sift 1 1/2 cups of the flour into the bowl and stir until mostly smooth. Cover with plastic wrap and set aside in a warm place for about 30 minutes. The mixture will expand, loosen in texture and will have large bubbles on the surface.
While that sits, generously butter a 12-cup Bundt pan and set aside. Place the dried fruit, 2 tablespoons of the brown sugar and all of the whiskey in a microwave-safe bowl. Stir until the sugar is dissolved. Heat in the microwave until hot and bubbling, 1 to 2 minutes. Stir and set aside to cool. In a medium bowl, whisk the remaining 1 1/2 cups flour with the cinnamon, allspice, nutmeg and salt.
Beat the butter with the remaining 1/2 cup brown and the granulated sugar with an electric mixer on medium-high speed until light and fluffy. Beat in the eggs, one at a time, until combined (the mixture may look slightly curdled at this stage), and then add 1 teaspoon of the vanilla. Beat in the yeast mixture and then reduce the speed to medium-low and gradually beat in the flour mixture. Add the plumped dried fruit with any remaining liquid and beat on medium speed until the fruit is well blended. The dough should be soft and elastic at this point.
Transfer the dough to the prepared Bundt pan and cover with plastic wrap. Let rise in a warm place until the dough fills the pan about three-quarters of the way, about 2 hours. When is the cake is almost done rising, preheat the oven to 375 degrees F.
Bake the cake until golden brown and a skewer inserted comes out clean, 40 to 45 minutes. Cool for 30 minutes in the pan on a wire rack. Loosen the sides with a small metal spatula and turn onto the wire rack to cool completely.
Before serving, stir the confectioners' sugar with the remaining 1/2 teaspoon vanilla and 1 tablespoon milk. Gradually add as much as needed of the second tablespoon of milk to make a thick glaze that will just gently run. Spoon over the top of the cake, allowing the glaze to slowly run down the outside and inside of the cake.
Cook's Note: This cake is great made a day or two in advance. Just hold off on the glaze until you are ready to serve.