Preheat the oven to 325 F degrees. Grease a loaf pan with cooking spray or butter.
Combine the wet ingredients: In a medium bowl mix the sugar, pumpkin, butter, eggs, sour cream and vanilla extract.
Combine the dry ingredients: In another bowl combine the flour, baking soda, baking powder, salt, pumpkin spice and cinnamon. Add the dry ingredients to the wet ingredients and stir, but do not stir too much, just until the flour has been incorporated into the wet ingredients. If the batter is too thick add a bit of water, I added 1/4 cup.If the batter is too thick add a bit of water, I added 1/4 cup.
Bake: Pour the batter into the prepared loaf pan. Transfer the loaf pan to the oven and bake for 70 to 80 minutes or until a toothpick inserted in the center comes out clean. Cool the pumpkin bread in the loaf pan for 10 minutes before removing it from the pan and finish cooling it on a wire rack.
Once the bread has cooled completely wrap it in aluminum foil or plastic wrap. It will stay fresh at room temperature for up to 3 days. You can also refrigerate it for up to 6 days.
Wrap the cooled bread tightly with aluminum foil or plastic freezer wrap, then place it in a freezer bag and freeze for up to 3 months.
If you froze the pumpkin bread, thaw it out at room temperature for about an hour, unwrap it then transfer it to a baking sheet or loaf pan and bake for about 5 to 10 min at 350 F degrees or until heated through.