In the bowl of an electric mixer, cream butter and brown sugar until light and fluffy. Add peanut butter and mix well. Add egg and vanilla extract and mix well.
Sift in flour, salt, baking powder and baking soda and mix on lowest speed until incorporated. Stir in chocolate chips.
Transfer dough to a bowl (or use the same bowl), cover with plastic wrap and refrigerate for a few hours or overnight.
Preheat oven to 325F (170C). Line baking sheets with baking paper. Measure out 2 ounces of dough (I didn’t measure in tablespoons, but I’d say it was a good rounded 2 tablespoons of dough) and place on the baking sheets about 2-3 inches apart. Bake about 15-17 minutes, rotating the trays if necessary, being sure to take the cookies out when they still slightly under-baked. Let cookies cool on the sheets for a couple of minutes before transferring to a wire rack, then enjoy!
Recipe by sweetest kitchen at http://www.sweetestkitchen.com/2012/02/chewy-peanut-butter-chocolate-chip-cookies/