In the oven place a baking sheet or aluminum foil on the bottom rack to catch any drips. Adjust an oven rack to be on the second level up from the bottom. Preheat the oven to 425°F.
To make pecan topping layer. In a small bowl mix together the granulated sugar, brown sugar, flour, cinnamon, salt, and chopped pecans. Cut in 7 tablespoons of cold butter with a pastry cutter, two knives, or two forks until the mixture is in pea sized chunks. Set bowl aside.
To make pumpkin pie layer. In a medium sized bowl, combine together the granulated sugar, brown sugar, flour, cinnamon, pumpkin pie spice, and salt. Add in the pureed pumpkin, eggs, and sour cream, mix until creamy.
To make apple layer. In a small bowl, combine together brown sugar, cinnamon, and flour. Toss with the sliced apples to evenly coat them.
Melt the butter in a 10-inch cast iron skillet over medium heat. Sprinkle the sugar over the melted butter. Cook for 3-4 minutes until the butter just starts to brown. Take skillet off the heat.
Add the apples in to the skillet, laying them out on the bottom in a layer that completely covers all of the open spaces. Pour the pumpkin mixture over the apples, spreading it evenly. Sprinkle the pecan crumble on the top of the pie leaving a 1/4-inch border of pumpkin around the edges without topping.
Place pie on the second from bottom rack. Bake for 10 minutes at 425°F, then drop temperature down to 350°F. Cook for 40-45 minutes, until a toothpick inserted in the center of the pie comes out clean.