Preheat oven to 350°F and spray a 9×13 inch pan with Baker’s Joy® No Stick Spray with Flour; set aside.
- In a medium bowl, whisk together the brown sugar, granulated sugar, pumpkin pie spice and salt.
- Pour in the melted butter and stir until fully blended.
- Add the flour and nuts, if using, and stir with a fork until the flour is absorbed and you have large clumps; set aside.
- In a medium bowl, whisk together the flour, pumpkin pie spice, baking soda and baking powder; set aside.
- In the bowl of a mixer, beat the butter on medium speed until creamy, about 1 minute.
- Add the sugar and mix on medium-high until fluffy, about 2 minutes.
- Add the molasses and mix on medium speed until well blended, scraping the sides of the bowl as needed.
- Add the eggs, one at a time and mix on medium speed to blend. Then stir in the vanilla.
- On low speed, add the flour mixture a little at a time until all has been added.
- Stir in the sour cream.
- Pour the cake mixture into the prepared pan and spread out evenly.
- Sprinkle the topping mixture over the cake, leaving some larger chunks intact.
- Bake for 45-55 minutes or until a toothpick inserted in the center comes out clean.
- Allow it to cool slightly before cutting.