Preheat oven to 350°F. Grease a 9x13-inch baking pan with cooking spray and set aside.

To make the topping, in a large bowl, combine the sugar, flour, salt, and cinnamon. Stir in the butter until the mixture comes together to form coarse crumbs. Stir in the pecans and set aside.

To make the filling, peel, core and thinly slice the apples. Toss together in a large bowl with the sugar, pumpkin pie spice and cornstarch until evenly combined; set aside.

To make the cake, in a large bowl whisk together the flour, baking powder, baking soda, salt, cinnamon and pumpkin pie spice. In the bowl of a stand mixer, fitted with the paddle attachment, cream together the butter with the sugars until light and fluffy, about 3 minutes. Stir in the eggs, one at a time, mixing well after each addition. Stir in the pumpkin and vanilla. Add the dry ingredients alternately with the buttermilk, starting and ending with the dry ingredients. Stir until just combined, after each addition, making sure to not overmix at this point.

Pour half of the batter into the prepared baking dish and spread out to an even layer. Top with the apple mixture. Then spread out the remaining batter over the top. Sprinkle the topping in an even layer, pressing down gently. Bake until the cake is golden brown and a toothpick, inserted in the middle, comes out clean, about 45 to 50 minutes. Remove from the oven and allow to cool before slicing and serving. Enjoy!