Preheat oven to 350 degrees
Prep an 8 x 8 inch baking pan with nonstick baking spray
Line the baking pan with parchment paper
Make the topping: add flour,cinnamon and brown sugar in a medium bowl, then whisk to combine
Cut butter in chunks, toss in with the flour mixture
With a fork mix the butter in with the flour combination, mix until the topping looks like coarse crumble.
Stir in 1⁄2 cup of chopped pecans, set aside
Make the Cake: in a bowl add flour, baking powder, baking soda, cinnamon, pumpkin pie spice and cinnamon, whisk to combine
In another bowl use an electric mixer blend the pumpkin puree, brown sugar, oil, eggs, vanilla, and sour cream, mix until completely combined
Combine the wet and dry ingredients together, stir until all of the ingredients are well mixed
add chopped pecans, stir until well incorporated.
Scoop the batter into the prepared pan, and spread it out
Add the crumble on top of the batter
If desired sprinkle with the garnish, chocolate chips and chopped pecans on top
Bake at 350 degrees for 28-30 minutes, (Or until a toothpick inserted in the center of the cakes comes out clean)
Serve warm or cool