Preheat oven to 375 degrees F.

In a large bowl, combine sugar, brown sugar and butter. Beat with an electric hand mixer until fluffy. Add the peanut butter, vanilla and egg, blend well. Add the flour, baking soda and salt to dough mixture and mix well. With a wooden spoon or rubber spatula, stir in butterscotch chips. Take small dollops of dough and shape, with your hands, into 1-inch balls. Place 2 inches apart on a cookie sheets. Make sure that the cookies are at leat 2 inches apart from each other because they will spread. Dip a fork into sugar and flatten the balls lightly with the fork in a crisscross pattern. Bake cookies for 6 to 9 minutes, or until golden brown. Remove cookies from cookie sheet immediately and place on wire racks to cool thoroughly. After cookies have cooled, dip in chocolate sauce.