Preheat oven to 350 degrees. Beat brown sugar, peanut butter, egg and vanilla extract in a medium bowl and blend until smooth.

Scoop 1 Tablespoon of dough and shape into a 1 1/2 inch ball. Place 2 inches apart on baking sheets.

Bake for 10-12 minutes or until set (note that dough will still be very soft at this point). Press chocolate kiss gently into center of cookie and let cool for ~5-10 minutes on baking sheet before transferring to cooking rack. Let cookies cool completely until fully set.