Begin by preparing the sweet potato. Pierce the skin of a medium sweet potato with a fork and microwave it for 5–7 minutes or roast in the oven at 400°F for 45–60 minutes until tender. Scoop out flesh and mash until smooth.

In a large mixing bowl, beat together ½ cup of softened unsalted butter with ½ cup of brown sugar and ½ cup of granulated sugar using an electric mixer on medium speed for about 2 minutes, until fluffy. Incorporate one egg, 1 teaspoon of vanilla extract, and the mashed sweet potato until fully combined.

In a separate bowl, whisk together 1 ½ cups of all-purpose flour, 1 teaspoon of cinnamon, ½ teaspoon of nutmeg, 1 teaspoon of ginger, 1 teaspoon of baking soda, and a pinch of salt.

Gradually add the dry mixture to the wet ingredients, stirring gently until just combined; do not overmix.

Drop rounded heaps of dough onto a lined baking sheet and sprinkle with chopped pecans or cinnamon sugar if desired. Bake in a preheated oven at 350°F for 10–12 minutes until edges are golden brown while the centers remain soft.

Let the cookies rest on the pan for about 5 minutes, then transfer to a wire rack to cool completely.