Preheat oven to 375. Lightly grease a baking sheet with cooking spray.
Cream together butter and sugars. Add vanilla and egg and mix well. Add puree and mix again.
In a separate bowl whisk together flour, salt, and baking powder.
Add dry ingredients to wet ingredients and mix until dough comes together.
Roll dough into 1 inch balls and place on baking sheet. Gently smash down each ball, just to flatten slightly.
Bake for 10-13 minutes until golden brown and cookies look "dry".
Immediately after removing from the oven, use the end of a wooden spoon (or similar object) to gently press a hole halfway into the cookie (not all the way through). Allow to cool completely.
When cookies have cooled, press a chocolate kiss candy into the center of each cookie. Store in airtight container.