Sweet Potato Snack Cake

Name: Sweet Potato Snack Cake
Ingredients: 3 ½ cups / 440g whole wheat pastry flour or all purpose, unbleached flour (I used all purpose, whole wheat will yield a awesomely tender crumb though, just take care not to under bake); 1 teaspoon baking soda; ½ teaspoon baking powder; 2 teaspoons cinnamon; 1 ½ teaspoons medium grain kosher salt; 2 cups minus 2 tablespoons / 375g sugar; 2 cups mashed sweet potato (about 6-8 small - medium sweet potatoes total); ¾ cup / 180g buttermilk room temperature; ¾ cup / 168ml sunflower oil or coconut oil, melted and cooled; 4 large eggs room temperature; 1 cup / 113g chopped pecans, toasted (you can have more pecans than this if desired, this recipe really is magical with those pecans!); ¾ cup / 128g bittersweet chocolate discs or a large chocolate bar chopped into large chunks (optional)