Preheat oven to 350°F and adjust the oven rack to middle-low position.
To make it possible to lift the pound cake from the pans, and if using loaf pans, spray the pans with nonstick spray and make “slings” for the pans. To make parchment paper slings, cut pieces of parchment paper long enough to hang over the edges of the pans by 2 inches and wide enough to fit into the pans (length & width). There should be two crisscross pieces of parchment per loaf pan. Spray the top side of the parchment with nonstick spray. Alternately, spray the pans with baking flour spray or, alternately, butter and flour the pans.
In a large bowl, whisk the flour, salt, and baking powder together. Set aside.
3 cups all-purpose flour, ½ teaspoon kosher salt, ½ teaspoon baking powder
In a large measuring cup, stir the buttermilk, vanilla extract, and almond extract together.
1 cup buttermilk, 2 teaspoons pure vanilla extract, 1 teaspoon almond extract
In the bowl of a stand mixer fitted with the paddle attachment, cream the butter and shortening together for 2 minutes.
1 cup unsalted butter, ½ cup vegetable shortening
Add the sugar, ¼ cup at a time, and beat until pale, yellow, creamy, and somewhat fluffy, about 3 minutes.
3 cups granulated sugar
Add the eggs, one-at-a-time, beating until well combined after each addition.
5 large eggs
Add the flour mixture to the butter mixture, alternately, with the buttermilk mixture. Start and end with the flour mixture. Mix just until no dry flour can be seen but don’t over-mix. Set aside while you make the filling.
To make the filling: In a medium saucepan, whisk the eggs until foamy. Add the granulated and brown sugars, salt, and melted butter, and whisk until well combined. Set the saucepan over medium-low heat, stirring often until the mixture is hot to the touch, but not boiling. Add the lemon juice and half of the chopped pecans and stir well.
3 large eggs, ½ cup granulated sugar, ¼ cup dark brown sugar, ⅛ teaspoon kosher salt, 3 tablespoons unsalted butter, ½ lemon, 2 cups toasted rough-chopped pecans
Pour ¼ of the cake batter into each of the 2 prepared loaf pans and sprinkle ¼ of the remaining pecans over the batter in each pan. Pour ¼ of the Pie Filling over the pecan layer in each pan (SEE NOTE). Use a thin knife to swirl the filling through the batter.
Halve the remaining batter and spread it over the pecans/pie filling layer in each pan.
Top each cake with half of the remaining pecans and half of the remaining Pie Filling.
Bake cakes at 350°F, set side-by-side, for 1-1½ hours. Turn the pans around after an hour and cover very loosely with foil. (My cakes took about 1½ hours, but start checking the cakes at 70 minutes and check every 5 minutes thereafter). The cakes are done when the internal temperature registers 210°F on an instant-read thermometer, or when a toothpick inserted in the middle of the cakes comes out clean.
Transfer the cakes to a cooling rack to cool 15 minutes then lift the cakes out of the pans by pulling up on the parchment slings. Cool the cakes completely before slicing.