FOR THE FILLING:
In 19th-century Appalachia, a stack cake served as a potluck wedding cake, as members of the community would contribute layers. It's easy to make, since the dough resembles that of giant sugar cookies.
Note: This cake has six layers, each baked individually. If you have a large oven and a big pan collection, you can bake them all at once. Otherwise, the recipe is based on the assumption that you'll be using three.
First, make the filling: In a 4-quart pot over high heat, combine cranberries, sugar, orange juice, and orange zest. Cover and bring to a boil; then reduce heat to medium-low. Simmer, stirring often, until cranberries soften, split their skins, and sauce thickens a bit, 10 to 15 minutes. Puree with a blender until smooth and creamy. Mixture should have the texture of ketchup. If too thick, add a few more tablespoons orange juice. Or cover and refrigerate up to 5 days.
FOR THE CAKE:
Butter and flour cake pans (see Note). In the bowl of a standing mixer (or using a hand-held mixer), cream sugars and butter together at medium speed until quite fluffy, 3 to 5 minutes. In a medium bowl, sift together flour, baking powder, baking soda, salt, and cinnamon. Set aside. In a small bowl, whisk together buttermilk, eggs, and vanilla.
Add a third of the flour mixture to butter/sugar mixture and mix just to combine at medium-low speed. Add half the buttermilk mixture and mix just to combine. Repeat, adding another third of the flour mixture, then remaining buttermilk mixture, then remaining flour mixture.
Turn dough out onto a lightly floured surface, knead four times to bring it all together, then roll into an even cylinder about 18 inches long. Cut cylinder into six equal parts (each 3 inches long), then press each part into a disk, wrap in plastic, and refrigerate at least 30 minutes and up to a day.
Preheat oven to 400° and set rack to middle position. On a lightly floured surface, roll out one disk to a 10-inch circle (use a bit more flour if it sticks). Using a cake pan as your guide, trim dough into a perfect 9-inch circle, then lay it in a pan to bake. Repeat with two more pieces.
Bake all three, rotating pans halfway through, until layers are lightly golden and just beginning to pull away from the sides, 10 to 12 minutes. Remove from oven and cool on wire racks 10 minutes. Remove layers and set aside. When pans are cool, butter and flour them once more and repeat rolling, cutting, and baking with the other three dough rounds.
Assemble the cake: Choose your prettiest, smoothest “top” layer and set it aside. Choose your bottom layer and use an offset spatula to spread about ⅓ cup filling over the top, all the way to the edges. Top with another layer and another ⅓ cup filling. Repeat three more times, then top with the prettiest layer. Cover with plastic wrap and refrigerate at least 24 hours, preferably 48, then dust top with confectioners' sugar, cut into thin slices, and serve.