PieCaken (Stacked Pecan Pie, Pumpkin Pie & Spice Cake)

Steps

1. Plan the bake and prep the pans: Position a rack in the center of the oven and preheat to 350°F. Line the bottoms of three 9-inch round cake pans with parchment and grease the sides — or use three 9-inch springform pans, which make releasing the two custard layers effortless. Set aside.
2. Make the pecan pie layer: In a large bowl, whisk the melted butter, brown sugar, and corn syrup until smooth. Whisk in the eggs, vanilla, and salt until fully combined, then fold in the chopped pecans. Pour into one prepared pan and bake at 350°F until the top is puffed and the center is set with just a faint jiggle, 45 to 55 minutes. Let cool completely in the pan, then refrigerate.
3. Make the pumpkin pie layer: In another bowl, whisk the pumpkin purée, heavy cream, brown sugar, eggs, cinnamon, ginger, nutmeg, cloves, and salt until completely smooth and streak-free. Pour into a second prepared pan. For the silkiest custard, set that pan in a larger roasting pan and add hot water halfway up the sides; bake at 350°F until the edges are set and the center jiggles as one solid mass, 40 to 50 minutes (55 to 60 in a water bath). Cool completely, then refrigerate.
4. Make the spice cake layer: In a large bowl, whisk the flour, both sugars, baking powder, baking soda, salt, cinnamon, ginger, nutmeg, and allspice. In a separate bowl, whisk the eggs, milk, oil, and vanilla. Pour the wet ingredients into the dry and stir just until no dry streaks remain — do not overmix or the cake turns tough. Scrape into the third prepared pan and bake at 350°F until a toothpick in the center comes out clean, 28 to 32 minutes. Cool in the pan 10 minutes, then turn out onto a rack and cool completely.
5. Chill everything: Refrigerate all three layers — in their pans or wrapped — until completely cold and firm, at least 3 hours, ideally overnight. Cold layers stack cleanly without tearing or squishing, and this rest is what makes the custards slice perfectly.
6. Make the cream cheese frosting: In a large bowl, beat the cream cheese and butter on medium speed until completely smooth and free of lumps. Gradually beat in the confectioners' sugar, then the vanilla and salt, and beat until light and fluffy. If the frosting feels stiff, beat in 1 to 2 tablespoons of heavy cream to loosen it.
7. Assemble the stack: Set the pecan layer, smooth side down, on a serving plate or cake board. Spread a thin, even layer of frosting over the top. Invert the pumpkin layer out of its pan and set it on top, then spread another thin layer of frosting. If the spice cake domed, trim the top flat with a serrated knife, then place it flat side up on top. The sturdy pecan base, soft pumpkin middle, and dry cake top are what keep the tower stable.
8. Crumb-coat and chill: Spread a very thin layer of frosting over the entire cake to trap crumbs. Refrigerate for 30 minutes until firm.
9. Finish the frosting: Spread the remaining frosting generously over the top and sides, swirling with an offset spatula. Chill the frosted cake for at least 2 hours (or overnight) so the layers set and the slices come out clean.
10. Slice and serve: Use a long, sharp knife dipped in hot water and wiped dry between cuts. For the cleanest slices, score the cake lightly first, then cut through. Serve chilled or at cool room temperature, and return any leftovers to the refrigerator within 2 hours.