In the bottom of the bowl of a stand mixer, whisk the yolks, whole egg, sugar, butter, buttermilk and 3/4 of the orange zest together (saving the rest for the filling).
Add 2 cups of the flour along with the yeast and salt; stir until evenly moistened.
Switch to the dough hook and add the remaining 1 3/4 cups flour and let the dough hook knead the mixture on low speed for 5 to 7 minutes. The dough should be soft and moist, but not overly sticky.
Scrape the dough into a large, lightly oiled bowl and cover it with plastic wrap. Let dough rise at room temperature until doubled, which will take between 2 and 2 1/2 hours.
Prepare the filling: Melt the butter and set it aside.
In a food processor, pulse the whole cranberries until they’re ground to a coarse rubble, but not fully pureed. Set them aside.
Butter a 9×13-inch baking dish.
Turn the risen dough out onto a floured work surface and roll it into a rectangle that is 18 inches wide and 12 or so inches long.
Brush the dough with the melted butter.
Sprinkle it with the brown sugar. Scatter the ground cranberries over it, then the remaining orange zest.
Roll the dough into a tight, 18-inch long spiral. Using a sharp serrated knife, very, very gently saw the log into 1 1/2-inch sections; you should get 12.
Arrange the buns evenly spread out in your baking dish. Cover with plastic wrap and refrigerate overnight, or up to 16 hours.
The next morning, take your buns out of the fridge 30 minutes before you’d like to bake them, to allow them to warm up slightly. Heat your oven to 350 degrees F.
Bake your buns until they’re puffed and golden, approximately 30 minutes. Transfer pan to a cooling rack and let cool slightly.
Make the icing by whisking the orange juice and powdered sugar together. Spread a little on each bun, or drizzle it over the whole pan. Serve immediately.