In a large bowl or stand mixer, cream together butter, 1/2 cup granulated sugar and brown sugar. Beat until light and fluffy. Mix in egg and vanilla, scraping bowl as needed. Add spices, salt and baking soda, followed by pumpkin puree. Mix until just combined. Add 1 cup of flour at a time until fully combined, increase speed after each addition. Mix until no streaks remain. Chill for at least 3-4 hours or until dough is firm but still manageable. 

Preheat oven to 350°F. Prepare a baking sheet with a silicone baking mat or parchment paper. 

Add remaining 1/4 cup granulated sugar to a small bowl. 

Use a small cookie scoop to scoop heaping mounds of dough. Shape dough into roughly 1-inch balls. Roll each ball in sugar and space 2-inches apart on prepared baking sheet. 

Bake for 10 minutes. While cookies are still on baking sheet, immediately press an unwrapped chocolate Kiss into each cookie. Immediately transfer to a wire rack to cool completely. 

Store cookies in an airtight container.