Heat oven to 350 degrees. In large bowl, using hand mixer or paddle attachment, cream shortening and brown sugar. Add egg and sweet potatoes; mix until combined.
In small bowl, combine flour, baking soda, salt and pumpkin pie spice. With mixer on low speed, slowly add flour mixture to egg mixture until well mixed. Using small cookie scoop, drop rounds onto greased baking sheets.
Bake 10-12 minutes, or until golden brown. Cool completely before frosting.
For frosting: In separate bowl, beat together butter, powdered sugar and maple extract until light and fluffy. Frost each cooled cookie.
Sprinkle with pecans and mini marshmallows, if desired. Carefully toast marshmallows with culinary torch, if desired, while avoiding melting frosting.