Preheat the oven to 375 degrees F and grease an 8" pan with cooking spray. Press a sheet of parchment paper into the pan so that it sticks nicely to the bottom with edges hanging over.

In a medium sized bowl whisk together the brown sugar, whole wheat pastry flour, pumpkin pie spice, cinnamon, nutmeg, baking soda, baking powder, and salt. Add in the melted butter and use a wooden spoon or your hands to mix the butter into the dough so that a crumbly dough begin to form.

Reserve roughly about a half cup of dough for the topping. Press the remaining dough into the baking pan to form a crust. Make sure the whole bottom of the pan is covered as evenly as possible. Set aside.

In the bowl of a stand mixer or using a hand mixer, mix together the pumpkin puree, honey, egg, vanilla extract and pumpkin pie spice until smooth and combined. Pour over the crust and use a spatula to spread evenly.

Mix walnuts, pumpkin seeds, pecans, or oats into the remaining dough and sprinkle chunks on top of the pumpkin filling. It's ok if some chunks are bigger and some are smaller. Cover most of the top. 

Bake for approximately 28 minutes, remove from oven and let cool. Cut into bars and enjoy!