1. Beat cream cheese, butter, granulated sugar and vanilla in large mixer bowl until light and fluffy. Stir together flour and salt; gradually beat into cream cheese mixture, beating until well blended. Divide dough into half; cover and refrigerate about an hour or until firm.
2. Remove wrappers from peanut butter cups. Carefully place each peanut butter cup on its side and cut through the cup, separating the top from the peanut butter filling and bottom. Set the peanut butter cup tops aside. Chop the bottom sections with a little bit of granulated sugar into very fine pieces; set aside. (The granulated sugar helps to keep the mixture from clumping.)
3. Heat oven to 350°F. Line cookie sheets with parchment paper or grease lightly. Roll half of dough at a time on lightly floured surface to a thickness of 1/8 inch. (Keep remaining dough in refrigerator until ready to use.) Cut into 3-inch squares. Use spatula to lift and place squares 1 inch apart on prepared cookie sheet.
4. Place about 1 teaspoon of chopped peanut butter cup mixture in center of each square. Cut from each corner of square to within 1/2 inch of center and filling. Bring every other point into center and press dough together to form pinwheel.
5. Bake 12 to 14 minutes or until lightly browned. Cool cookies completely. Sprinkle cookies with powdered sugar. "Glue" peanut butter cup top to cookie with about 1/4 teaspoon peanut butter to form center of pinwheel. Makes about 36 cookies.