Preheat the oven to 350 degrees F. Line 3 cookie sheets with parchment paper. Place the shortening, sugars, peanut butter, egg, and vanilla in the bowl of a mixer fitted with a paddle and beat on medium speed stopping occasionally to scrape down the sides of the bowl, until well combined, about 3 minutes. In a separate bowl, combine the flour, baking powder, and salt. Add the flour mixture to the peanut butter mixture and beat on low speed until well combined, 1 to 2 minutes. Add the peanuts and beat 30 seconds longer.
Drop the batter by tablespoonfuls on the prepared cookie sheets, about 1 1/2 inches apart. Roll each tablespoon of batter into a ball. Working one at a time, dip the tines of a fork in sugar and press down each ball into a 1 1/2- to 1 3/4- inch round, forming a crosshatch on top. Transfer to the oven and bake until the edges of the cookies are lightly browned, 12 to 14 minutes. Cool cookies on cookie sheet on a rack for 5 minutes. Transfer to the rack and cool completely.
Reprinted with permission from Cookies for Kids' Cancer: Best Bake Sale Cookbook, by Gretchen Holt-Witt, copyright (c) 2011. Published by Wiley.