2 cups all-purpose flour

1/2 tsp baking soda

1/4 tsp salt

1 1/2 sticks (3/4 cup) unsalted butter, room temperature

3/4 cup smooth peanut butter, preferably natural

1/2 cup sugar

1/2 cup packed light brown sugar

1 large egg

1 tsp pure vanilla extract

Instructions:

In a bowl, whisk together flour, baking soda, and salt; set aside.  Place butter, peanut butter, and both sugars in the bowl of an electric mixer fitted with the paddle attachment; beat on medium-high speed until light and fluffy, 2 to 3 minutes.  Add the egg and vanilla, and beat to combine, scraping down the sides of the bowl.  With mixer on low, add reserved flour mixture and beat until incorporated, about 1 minute.

Divide dough in half, and shape into two flattened disks.  Wrap in plastic and refrigerate at least 30 minutes or overnight.

Preheat oven to 325 degrees.  Line two large baking sheets with parchment paper.  If you refrigerated overnight, let dough stand at room temperature to soften slightly.)  On a lightly floured work surface, roll out dough to a scant 1/4-inch thickness.  Using a sharp knife or a pizza cutter, cut dough into 2 1/2-by-1-inch rectangles. Transfer cookies to prepared baking sheets, placing 1 1/2 inches apart, and refrigerate until firm, about 15 minutes.