Preheat the oven to 350 degrees F. Grease a square baking dish with cooking spray and set it aside.
In a medium bowl, combine the dry ingredients: all-purpose flour, pumpkin pie spice, baking soda, baking powder, and salt. Mix well and set aside.
In a separate large bowl, combine the pumpkin puree, sugar, oil, milk, and vanilla extract. Whisk vigorously until all the ingredients are well combined.
Gradually add the dry ingredients into the wet mixture and mix thoroughly to create a smooth batter without any lumps. Pour the batter into the prepared baking dish.
As the batter bakes, prepare the topping: combine flour, brown sugar, pecans, butter, and cinnamon. Mix the ingredients until well incorporated.
Sprinkle the prepared topping evenly over the batter in the baking dish. Bake the coffee cake for 40-45 minutes, or until a toothpick inserted into the center comes out clean.
Once baked, allow the cake to cool for about 10 minutes before slicing and serving.