Preheat oven to 350 degrees
Make the crumble - In a small bowl, mix flour, brown sugar and spices together. Cut in the butter with a fork or pastry cutter and mix until it resembles coarse crumbs. Place in the freezer while preparing bread batter. Don't skip this step, it helps keep the structure of the crumb so it doesn't melt.
In a large bowl, whisk together the oil, granulated sugar, and brown sugar until the sugars are dissolved.
Add the egg, sour cream and vanilla and whisk until smooth.
Stir in the pumpkin puree
In a separate bowl, whisk together the flour, cocoa powder, baking soda, and spices
Gradually add the dry ingredients to the wet ingredients, folding with a spatula until just combined. Do not overmix.
Place chocolate chips in a microwave safe bowl and heat at 30 second intervals, stirring in between until it's just melted.
Gently fold in the melted chocolate chips
Pour the batter into the prepared loaf pan lined with parchment paper or with non-stick spray, and spread across the top evenly using a rubber spatula.
Take the crumble from the freezer and sprinkle evenly across the batter
Bake for 50-60 minutes at 350 degrees, or until a toothpick inserted into the center comes out clean or with a few moist crumbs attached.
Let the bread cool in the pan for about 10 minutes before transferring it to a wire rack to cool completely.