Beat sugar and butter together in a bowl using an electric mixer until smooth and creamy; beat in egg until smooth. Beat in pumpkin purée, vanilla extract, cinnamon, salt, and baking powder. Stir in flour just until combined. Refrigerate dough for 2 hours to overnight.

Preheat the oven to 400 degrees F (200 degrees C).

Roll dough on a floured work surface. Cut into shapes using cookie cutters; arrange on a baking sheet.

Bake in the preheated oven until edges are lightly browned, 6 to 8 minutes.