Place oven rack in the middle position.Using a hand mixer or a stand mixer, mix peanut butter and sugar till fluffy. Add the egg and mix till dough is smooth. Roll the dough into 2 - 2 ½ inch balls. Roll in the extra granulated sugar and place on a non stick cookie sheet- about an inch to an inch and a half apart. Bake in the oven for 9 ½ minutes. 

While cookies bake line counter top with parchment paper or slip mats for cooling. I do not recommend using a rack because cookies are very soft when the come out of the oven. Remove from oven and transfer to counter. Allow cookies to cool for a few minutes. While cookies are soft press a kiss into the center of each cookie. I do not press it in too far because it will melt into the cookie. Enjoy with a glass of milk!