In a very large bowl, whisk the cream, ¾ cup lukewarm water, 6 tablespoons sugar, and the yeast. Add 4 of the eggs and whisk until smooth. Add half the flour and all of the salt and whisk until the mixture is smooth, shiny, and stringy, about 2 minutes. Swap the whisk for a wooden spoon and add the rest of the flour, stirring until fully incorporated into a very soft dough. Scrape the dough from the sides of the bowl, and cover the bowl with a heavy towel. Set aside at room temperature until the dough rises a few inches (it won’t double), about 1 hour. (When poked, the dough will be soft but shouldn’t stick to your finger.)
Meanwhile, prepare the fruit filling: If the fruit is very hard and dry, cover it in boiling water and soak until tender, about 1 hour. Drain, discard the soaking liquid, and coarsely chop. Transfer the chopped fruit to a medium bowl, add the candied ginger, and stir to combine. Set aside.
In a small bowl, combine the remaining ¾ cup of sugar with the cinnamon and cardamom and set aside. In another small bowl, whisk the remaining egg with 1 teaspoon of cold water and set aside to use as an egg wash.
Grease a large, rimmed baking sheet or rectangular cake pan with butter or lard and line with parchment paper.
Generously dust a work surface and rolling pin with flour. Turn the dough out onto the surface and dust it generously with more flour. Use your hands to pat the dough into an even rectangle, then roll it out into a 1⁄3-inch-thick sheet, about 20 x 25 inches. Brush the dough with the condensed milk, then sprinkle the spice mixture over it, followed by the dried fruit, spreading the fillings evenly over the dough all the way to the edges. Divide the dough into 5 long strips, and roll each lengthwise into a fat snake, about 1½ inches wide, pinching the seams shut. Press one end of all 5 strands together, with the opposite ends fanning out toward you, with 3 strands to the right and 2 strands to the left. Bring the strand farthest to the right over the center 3 strands so it falls between the 2 strands on the left. (You will now have 2 strands on the left and 2 on the right.) Next, bring the strand farthest to the left over the other 2 strands on the left so it lands in the center of the other 4 strands. Stretching the dough as little as possible, continue braiding the strands in this manner until you have a fat, braided loaf. Press the ends together, then wrap the loaf into a wreath shape, pressing the 2 ends of the braid together. Carefully lift the braid into the pan (you might need a second set of hands for this) and gently adjust the dough so it keeps its wreath shape, stretching as needed to even out the braid and tucking in the ends. Cover the cake with a dry towel and let rise at room temperature until the dough is slightly puffed, about 45 minutes.
Preheat the oven to 425°F. When the cake has risen, carefully brush it all over with the egg wash. Transfer to the oven and bake until dark amber-brown, 25–30 minutes. Lower the oven to 325°F, and continue baking until the internal temperature registers 190°–195°F, 20–25 minutes more.
Remove the cake from the oven and let cool slightly. Dust with powdered sugar, and serve warm or at room temperature.