Heat the milk in a small saucepan over medium-high heat until scalded, then cool to wrist warm or around 110 °F (43 °C). Pour into a medium bowl and whisk in the yeast. Beat in ½ cup of the flour, then cover the bowl with a tea towel and let stand in a warm place while you prepare the rest of the ingredients.
In the same saucepan, combine dried cranberries, candied orange peel and rum. Warm gently, then turn off heat and let soak.
In the bowl of a stand mixer fitted with the paddle attachment, cream ½ cup (8 tablespoons) of the soft butter with ½ cup of the sugar until light and fluffy. Beat in the eggs, one at a time, followed by the salt and cardamom. Tip in the yeast sponge and add ½ cup of the flour. Mix on low speed until the dough comes together.
Switch to the dough hook and add the remaining 2¼ cups flour, ½ cup at a time, mixing on low speed until a soft dough forms. Knead on low speed for 5 minutes. Remove the dough hook, cover the dough with a tea towel and let rise in a warm place for 1 hour or until doubled in size.
On a lightly floured counter, roll out dough to a 12 x 16-inch rectangle. Spread the remaining ¼ cup soft butter in an even layer over the dough, going right to the edges. Mix the remaining ¼ cup sugar with cinnamon and allspice, then sprinkle evenly over the butter. Evenly scatter soaked fruit over the buttered dough. Starting from a short end, tightly roll the dough into a log. Using a sharp knife, cut the dough into 12 buns, each 1-inch thick. Gently reshape them into rounds if they get overly squashed.
Butter two 13 x 18-inch rimmed baking sheets. Place 6 buns on each sheet and cover loosely with plastic wrap. Refrigerate overnight.
In the morning, allow buns to rise in a warm place for about 1½ hours or until doubled in size. You can do this step in the oven, with the oven turned off but the oven light turned on. If you do this, make sure to remove them before preheating the oven.
Preheat oven to 350 °F (175 °C) and position oven racks in the upper and lower thirds of the oven. Remove plastic wrap and bake buns for 22 to 24 minutes, rotating once, until golden brown. Dust with powdered sugar and serve warm.
Notes
Original recipe calls for slivered almonds, but I didn't have any. Use ½ cup if you want to add them, scattered over dough along with rum-soaked fruit.Recipe from page 37 of The Simple Bites Kitchen: Nourishing Whole Food Recipes for Every Day by Aimee Wimbush-Bourque, published by Penguin. Get your copy of the book on Amazon.