With an electric mixer with a paddle attachment, cream butter and brown sugar at medium speed until fluffy.
Beat in egg and vanilla.
In a separate bowl, combine flour, pumpkin spice and salt.
Slowly add flour mixture to wet ingredients until dough forms.
Turn out dough on surface and knead until smooth.
Place back in bowl, cover and refrigerate for 15-30 minutes.
When ready, let dough sit out for a few minutes to soften.
Preheat oven to 350° F.
Roll dough into large balls, about ¼ cup in size (70 grams).
Roll in sugar (optional) and place on an uncoated aluminum baking sheet.
To stamp, press square stamp down on dough in circular motion until the stamp hits the surface and dough spreads past the outside edges of stamp.
Twist stamp back and forth and slowly tilt to release from dough.
Remove excess dough around design if desired.
Repeat with other stamp designs.
Bake for 12-15 minutes.
Let cookies cool on baking sheet for 5 minutes and carefully remove to cool completely on a wire rack.
Repeat steps with remaining dough.
