Preheat oven to 350°. Spray a 9-inch round cake pan with cooking spray.
In a medium bowl, whisk together ¼ cup flour, ¼ cup granulated sugar, ¼ cup brown sugar, 1 teaspoon pumpkin pie spice, and 1 teaspoon cinnamon. Using a pastry blender or 2 forks, cut in butter until mixture has a fine, moist, sand-like consistency. Stir in pecans. Set aside.
In a large bowl, whisk together baking powder, baking soda, salt, pepper, remaining 1½ cups flour, remaining 1 teaspoon pumpkin pie spice, and remaining ½ teaspoon cinnamon.
In another bowl, stir together pumpkin purée, eggs, molasses, melted butter, remaining ¼ cup granulated sugar, and remaining ¼ cup brown sugar. Gently fold in flour mixture until well combined.
Pour batter into prepared pan, smoothing with an offset spatula. Sprinkle pecan mixture over batter to cover completely. (If there are any spots that look dry, then dot with a pat of butter.)
Bake until a wooden pick inserted in center comes out clean, 35 to 40 minutes. Serve warm.
Recipe by TeaTime Magazine at https://teatimemagazine.com/enjoy-a-holiday-whodunit-with-liz-irelands-new-mrs-claus-mystery/