- Preheat oven to 350 degrees Fahrenheit and prepare a 9x5-inch loaf pan by spraying it with non-stick spray or lightly greasing it. 
- In a medium-sized bowl, whisk together flour, baking soda, baking powder, spices, and salt. Set aside. 
- In a large bowl, add the egg, pumpkin purée, brown sugar, granulated sugar, vegetable oil, sour cream, and vanilla. Mix to combine. 
- Add the dry ingredients to the wet and mix until just combined. Do not overmix.  
- Turn the batter out into the prepared pan and use a spatula to evenly spread it.  
- Bake for 50 minutes, or until a toothpick inserted into the center comes out clean. Keep an eye out for the top browning too quickly. Tent the loaf pan with foil mid-way through baking if needed. (If using a dark coated pan, start checking for doneness at the 40 minute mark) 
- Allow the bread to cool completely. 
- While the bread cools, make the cream cheese frosting.