Preheat oven to 350 degrees. Grease pan 2 , 9×5 inch loaf pan with cooking spray; set aside.
In a small bowl, mix together, pumpkin, sour cream , eggs, orange zest and vanilla until smooth; set aside.
In a another medium bowl , blend together all the dry ingredients – Flour, sugars, baking powder, baking soda, cinnamon , nutmeg, allspice and salt.
Gradually add wet ingredients ingredients to dry ingredients, until fully combine.
Pour in melted butter and continue stirring until butter has been fully incorporated into the mixture . Divide batter in two.
Mix in chocolate chips , if desired to one pan. Add more chocolate chips if making chocolate pumpkin bread.
Scrape down sides and pour batter into the pan and spread evenly.
Pour the batter into the prepared pans and bake for 55-60 minutes or until a toothpick inserted in the center comes out clean.
Let the pumpkin bread remain in the pans about 10 minutes,before removing , then turn out onto a wire rack to cool completely.