Preheat the oven to 375
In a medium mixing bowl, sift together the flour, baking soda, salt, and cinnamon
In a large mixing bowl, add the butter, peanut butter, white sugar, and brown sugar
With an electric mixer, beat the butter, peanut butter, white sugar, and brown sugar until smooth and creamy
Add the egg and vanilla, and beat with the mixer until thoroughly incorporated
Add the dry ingredients to the large bowl, and beat with the mixer to combine fully until a soft dough forms
Using approximately 1 T of dough at a time, use your hands to roll the dough into neat little balls. Roll the balls in the extra sugar, and place on an ungreased cookie sheet
Put the cookie sheet in the oven and bake the cookies for 8 minutes, until the dough has begun to set but is still a bit soft
Removing the cookie sheet from the oven, press a Hershey's kiss into the center of each cookie
Return the cookies to the oven and bake for another 2-3 minutes, until it is fully cooked and the kiss has turned melty