Preparation: Heat the oven to 350°F / 180°C. Line your loaf pan with parchment paper.Pierce each sweet potato a few times with a fork and microwave for about 7 - 10 minutes, or until a knife slides through easily.Cut open, scoop out the flesh (careful it's hot), add it to a large mixing bowl, and mash it until smooth. You'll need about 2 cups cooked sweet potato flesh.
Mix wet and spices: Whisk in ¾ cups sugar, ½ cup Greek yogurt, ⅓ cup milk, ¼ cup olive oil, 1 large egg, and 1 teaspoon vanilla extract until creamy. Stir in 2 teaspoons cinnamon, 1 teaspoon ground ginger, ¼ teaspoon ground clove, and ¼ teaspoon allspice until evenly mixed.
Mix in dry ingredients: In another bowl, whisk together 2 cups all purpose flour, 2 teaspoons baking powder, 1 teaspoon baking soda.Add the dry ingredients to the wet mixture and stir gently until just combined — stop as soon as no flour streaks remain. Fold in ¾ cup chopped dark chocolate bar.
Bake: Pour into the prepared loaf pan and smooth the top. Bake for 50–55 minutes, or until a toothpick inserted in the center comes out clean.Let cool 10 minutes in the pan, then transfer to a rack. Serve warm or at room temperature.
