Preheat the oven to 350°F
Prepare an 8x4 inch loaf pan with non-stick spray and set aside.
In a large bowl, whisk together the flour, sugars, baking powder, baking soda, salt, and pumpkin pie spice.
In a medium size bowl, whisk together the vegetable oil, eggs, buttermilk, and pumpkin puree.
Add the liquid ingredients to the dry ingredients and stir to combine.
Fold in the chocolate chips.
Pour the batter into the prepared loaf pan.
Bake for 70-75 minutes, or until the top is lightly golden and a toothpick inserted in the centre of the loaf comes out clean.
Remove from the oven and move to a cooling rack. Allow the loaf to cool for 10 minutes, then tip the loaf out of the pan to continue cooling.