How to Make It
Make the cakes Preheat the oven to 350° with racks positioned in the upper and lower thirds. Butter three 9-by-9-inch metal cake pans and line them with parchment paper; allow 2 inches of overhang on 2 sides. Butter the paper.
In a medium bowl, whisk 2 1/4 cups of the flour with the baking soda, baking powder and salt. In a large bowl, whisk the melted butter with the granulated sugar, buttermilk and eggs until well combined. Whisk in the dry ingredients until just combined.
Divide the batter among 3 medium bowls (1 1/2 cups per bowl). Whisk the pumpkin puree, pumpkin pie spice and the remaining 1 tablespoon of flour into one of the bowls, then scrape the batter into one of the prepared pans. Fold the cranberries and cornmeal into another bowl and scrape into a second prepared pan. Fold the pecans into the final bowl and scrape the batter into the last prepared pan.
Transfer all 3 pans to the oven and bake the cakes for about 15 minutes, rotating halfway through, until a toothpick inserted in the center of each cake comes out clean. Let the cakes cool in the pans for 15 minutes, then invert onto a rack to cool completely. Peel off the parchment paper.
Meanwhile, make the frosting In the bowl of a stand mixer fitted with the paddle, beat the cream cheese, butter, confectioners’ sugar and a pinch of salt until smooth.
Place the pecan layer on a platter. Scrape 3/4 cup of the frosting on top and spread to the edge. Top with the cranberry layer; scrape another 3/4 cup of the frosting on top and spread to the edge. Top with the pumpkin layer. Spread a thin layer of frosting all over the cake and refrigerate until set, 15 minutes. Spread the remaining frosting all over the cake. Refrigerate until firm, at least 30 minutes, before serving.