Preheat oven to 350 Degrees Fahrenheit.175 Celsius.
Using the paddle attachment on your mixer, cream together butter, sugar and brown sugar until light and pale yellow.
Add the egg, pumpkin, vanilla and all spices. Cream together for about one minute until pale and creamy.
Sift together flour, salt and baking powder. Add in slowly, on low speed until everything is combined. The dough should be slightly wet, but not sticky.
Remove dough from the mixer bowl and turn onto a lightly floured surface, knead together for a few turns until all the dough comes together to form one ball. Do not refrigerate the dough! Roll out the dough to your desired thickness, I like about a quarter inch. Cut your desired shapes and lay out on a parchment lined cookie sheet. You can shape the scrap dough back together, roll out and cut again until all the dough is used.
Bake cookies for 8-10 minutes until just set. They should be even in color, not browning on the edges.
Cool on a rack then decorate with icing.