Preheat the oven to 350 degrees F.
In a large bowl, cream together the butter, 1/2 cup of the sugar, and vanilla. Add the toasted pecans and potato chips and stir well. Add the flour and stir to combine.
Place the remaining 1/2 cup sugar in a shallow bowl.
Form the mixture into small balls, about 1 tablespoon each, and place on an ungreased baking sheet.
Dip the bottom of a heavy flat-bottomed glass in the remaining 1/2 cup sugar and flatten the cookies on the baking sheet, dipping in sugar before flattening each cookie. Bake the cookies until light golden brown, 14 to 16 minutes.
Using a spatula, transfer the cookies to a wire rack to cool. (The cookies will keep in an airtight container at room temperature for up to 3 days.) When cookies have cooled, dip 1 half of each cookie in the chocolate sauce, if desired. Let harden on a wire rack.
Yield: about 3 1/2 dozen