Heat oven to 375 degrees F. Combine peanut butter, shortening, brown sugar, milk and vanilla in a large bowl. Beat at medium speed until well blended. Add egg, beat just until blended. Combine flour, salt, and baking soda. Add to creamed mixture at low speed. Mix just until blended. Shape into 1-1/2 inch balls. Roll in chopped peanuts. Press center with teaspoon. Bake 7 to 8 minutes. Press mini peanut butter cup into depression.