In a large bowl, beat at medium speed butter, sugar and salt until light and fluffy.
Add egg yolks, cream and vanilla. Beat 2 min until fluffy.
Gradually add flour with wooden spoon until well combined and dough is smooth.
Divide dough into 2 parts. Shape into 2 balls. Refrigerate covered for 2 hours.
Preheat oven 325 degrees.
It's important to roll VERY thin so the sandwich in the end is still delicate and thin. Cut with cookie cutter and bake for 12 to 15 minutes or until edges start to turn a light golden brown. Do not over bake.
She makes solid top and bottom. Once cooled spread jelly or preserve on one cookie, top with another. Powdered sugar on both sides. Makes about 3 dozen. She always doubles recipe.