Preheat oven to 325°F. Turn the base of an 8-inch springform pan upside down so you can easily slide the cake off. Lightly spray the pan with vegetable cooking spray. Line the bottom with a round piece of parchment paper. Set aside.
In a large mixing bowl, whisk together the flour, salt, baking powder, baking soda, granulated sugar and pumpkin pie spice. Make a well in the center and set aside.
In a small mixing bowl lightly whisk the eggs. Add the pumpkin puree, melted cooled butter, vanilla and milk. Fold together with a rubber spatula until blended.
Pour the pumpkin mixture into the flour mixture and fold together with a spatula until the flour is incorporated. The batter will be thick.
Gently scoop the batter into the prepared pan and smooth the top with an off-set spatula or back of a spoon. Set the cake aside and allow it to rest for 10-15 minutes before baking. This step helps give it some loft and puffiness. When ready to bake, top with pecan crumble.
Bake at 325F until a wooden skewer comes out with clean, about 55-60 minutes. Tent with foil after 30-minutes to prevent over-browning of the pecan topping.
Allow the cake to cool on a rack for 30 minutes before removing the sides of the pan. Slide onto a serving plate, cut into wedges and enjoy slightly warm or cooled. Store leftovers in a sealed container at room temperature for a day or two, or refrigerate for longer storage.