Preheat oven to 350 °F. Mix the flour, baking soda, baking powder, cinnamon, all spice, and salt in a bowl and put aside
In the bowl of a stand mixer, add the room temperature, softened butter and sugar and mix on medium high until soft and creamy (about a minute or two). Add the eggs and mix on medium until combined. Add the pumpkin puree and mix for a few seconds until combined. (only mix until combined, do not over do it).
Slowly add in the dry ingredients while your mixer is running on medium speed until everything is fully combined. Fold in sour cream.
Transfer the batter to a greased loaf pan and bake for 1 hour and 10 minutes or until a toothpick placed in the center comes out clean.