Preheat oven to 350℉. Line rimmed baking sheets with silicone baking mats or parchment paper.
Combine flour, baking soda, baking powder, cinnamon, nutmeg, and salt in a medium bowl. In a large mixing bowl, beat sugar and butter until well blended. Beat in pumpkin, egg, and vanilla until smooth. Gradually beat in flour mixture. Drop by rounded teaspoon onto prepared baking sheets.
Bake for 15 to 18 minutes or until the edges are firm. Cool on baking sheets for 2 minutes then remove to wire racks to cool completely.