Peanut Butter M&M Cookies

Preheat oven to 350°F, and prepare two cookie sheets by lining each of them with a sheet of parchment.
In a mixing bowl, cream the 1/2 cup shortening, 1/2 teaspoon vanilla, 1/2 cup granulated sugar and 1/2 cup brown sugar until thoroughly mixed and smooth, about 2 minutes. Add the egg. Scrape down the sides and bottom of the bowl, add the peanut butter, and mix well.
Whisk the 1 1/2 cups flour, 1 teaspoon baking soda, and 1/4 teaspoon salt together in a medium bowl. Add to the peanut butter mixture, and mix completely. Mix in 1/2 cup M&M's.
Use a #60 cookie scoop (1 tablespoonful of dough) and place the dough onto cookie sheets. Make a crisscross pattern in the top of each cookie using a fork.
Bake about 8-10 minutes, or until firm. Upon removing cookies from the oven, use the remaining 1/4 cup M&Ms to place additional candies on the tops, gently pressing them into the cookie, if desired. Cool on baking sheet for about 5 minutes before transferring to a wire rack to cool completely.