I saw this recipe on Smitten Kitchen  and just had to try it (and speaking of Smitten Kitchen, I must say, I love her site. She has the best recipes — both baking and regular cooking). Oh how I adore a good, homemade peanut butter cookie. And these cookies are DELICIOUS. I normally only have a bite or two of the treats that I bake (I have a sweet tooth, but luckily, it doesn’t take much to satisfy). Well, I’ve already consumed two of these cookies and I’m not going to lie, I’ll probably have a couple more. Diet, what?
Anyway. I’m in the process of moving, so I’ve packed up all of my baking gear except what is required to make cookies. So you’ll probably be seeing a lot of cookies on here in the next week or so. :)
Peanut Butter Cookies
Recipe source: Smitten Kitchen 
1 1/4 cups all-purpose flour
3/4 teaspoon baking soda
1/2 teaspoon baking powder
1/4 teaspoon salt
1/2 cup unsalted butter, softened
1 cup peanut butter at room temperature
3/4 cup sugar
1/2 cup firmly packed light brown sugar
1 large egg, at room temperature
1 tablespoon milk
1 teaspoon vanilla extract
1/2 cup peanut butter chips
1/2 cup chocolate chips
For sprinkling: 1 tablespoon sugar, regular or superfine
Preheat oven to 350 degrees.
In a large bowl, combine the flour, the baking soda, the baking powder, and the salt. Set aside.
In a large bowl, beat the butter and the peanut butter together until fluffy. Add the sugars and beat until smooth. Add the egg and mix well. Add the milk and the vanilla extract. Add the flour mixture and beat thoroughly. Stir in the peanut butter and chocolate chips. Place sprinkling sugar — the remaining tablespoon — on a plate. Drop by rounded teaspoonfuls into the sugar, then onto ungreased cookie sheets, leaving several inches between for expansion. Using a fork, lightly indent with a crisss-cross pattern (I used the back of a small offset spatula to keep it smooth on top), but do not overly flatten cookies. Bake for 10 to 12 minutes. Do not overbake. Cookies may appear to be underdone, but they are not.
Cool the cookies on the sheets for 1 minute, then remove to a rack to cool completely.