In a large mixing bowl, whip the butter till it’s pale and fluffy.
Add the white sugar and brown sugar and beat 1-2 minutes until smooth.
Add the egg and the vanilla and beat another 1-2 minutes.
Add the sweet potato puree and mix thoroughly.
In a separate bowl, mix together the dry ingredients: flour, cinnamon, baking powder, baking soda, salt, and allspice.
Gradually add the dry ingredients to the sweet potato mixture and mix till well combined.
Stir in ½ cup chopped pecans (additional pecans are sprinkled on top in later step).
Using a 1 ½ Tablespoon cookie baller, scoop and place balls 2 inches apart on a cookie tray lined with a silicone baking mat or parchment paper.
From the remaining ¼ cup chopped pecans, sprinkle a few pecan pieces onto the top of each cookie.
Bake 12-13 minutes until the edges start to golden.
Remove tray from the oven and immediately transfer the cookies to a cooling rack. Allow to cool completely.
Marshmallow Topping
In a small bowl, mix the powdered sugar and cinnamon.
Add the mini marshmallows to a microwave safe bowl, and heat on high for 20 seconds.
Immediately stir the marshmallows, then place the bowl back in the microwave and heat on high for another 20 seconds.
Stir the marshmallows until they are completely melted.
Spoon the melted marshmallows into a pastry bag with a small round top (Wilton #4).
Pipe a zig-zag pattern across each cookie.
Using a sifter, sprinkle a little of the powdered sugar and cinnamon mixture over each cookie to reduce marshmallow stickiness. The marshmallow topping should fully solidify within 30 minutes.