Pre-heat oven to 350° F. Prepare pan by lining it with parchment paper or use baking spray.
Combine all dry ingredients - flour, salt, baking soda, baking powder, spices and sugar.
Make a well in the center of the flour mixture and add wet ingredients - eggs, sweet potato puree and oil.
Mix with a spoon or a hand mixer. Stir in chopped walnuts last.
Spoon into the prepared loaf pan.
Bake on center rack for 50 to 60 minutes. Test by inserting a wood screw into the split crust.
Remove from oven and let rest for 5 minutes. Remove from pan and allow to cool on a wire rack before slicing.