Preheat oven to 300° Fahrenheit.
In a large mixing bowl, combine dry ingredients – flour, sugars, baking soda, cinnamon, ginger, nutmeg, cardamom, turmeric, and pepper and set aside.
In a separate large bowl whisk together mashed sweetpotato, eggs, yogurt, oil, yogurt, vanilla until well combined.
Pour wet ingredients over the dry ingredients and fold to incorporate fully with no visible clumps (do not over-mix).
Pour batter out into greased loaf pans and lightly smooth tops.
Bake for approximately 70 minutes or until top is domed and springy to the touch and tester comes out clean.
Hint: Tint pans with foil if top is browning too fast before interior fully cooks.
Allow bread to cool in pan for 10 minutes and then turn onto wire cooling rack to cool completely.