Preheat your oven to 350°F (175°C) and grease a 9.25 x 5.25 inch loaf pan.

In a large mixing bowl, combine softened butter and granulated sugar. Beat until light, fluffy, and pale, about 3-4 minutes.

Add the eggs one at a time, mixing well after each addition. Stir in the vanilla extract and mashed sweet potatoes.

In a separate bowl, whisk together flour, baking soda, salt, ground cinnamon, and nutmeg.

Gradually add the dry ingredients to the wet mixture, stirring gently until just combined.

In a small bowl, blend 0.25 cup of granulated sugar with the remaining ground cinnamon.

Pour the batter into the prepared loaf pan and sprinkle about ¾ of the cinnamon sugar mixture on top.

Bake for 55-65 minutes, checking for doneness with a toothpick.

Let the bread cool in the pan for about 15 minutes, then transfer to a wire rack to cool completely.