In a large bowl, whisk together flour, cocoa powder, pumpkin pie spice, baking soda, baking powder, and salt.
In another large bowl, combine melted butter, sugar, sour cream, vanilla, egg and egg yolk until smooth. Fold in pumpkin puree.
Combine wet and dry ingredients. Fold in 1 cup of chocolate chips.
Pour batter into loaf pan. Top with remaining chocolate chips.
Bake 50-55 minutes.
Let cool 15 minutes before carefully removing loaf to cool on rack.
Video
Notes
This loaf of pumpkin bread will stay fresh (stored in a container) for 3 days. It also freezes well. If you don't have pumpkin spice you can use 1 1/2 teaspoons cinnamon, 1/2 teaspoon nutmeg, 1/2 teaspoon ground cloves, and 1/2 teaspoon ginger.