Butter Cookies

Cream butter, sugar, and salt with mixer at medium speed until light and fluffy.  Add yolk, beat well, then add eggs and vanilla; continue beating until well incorporated.  Add flour and beat on low speed until flour is just mixed.  Divide dough in half and wrap in plastic. Refrigerate at least 1 hour, until firm.

Adjust oven racks to upper and lower-middle positions and preheat to 375º.  Line 2 baking sheets with parchment paper.

Remove one disk of dough from refrigerator and cut in half.  Return unused portion to fridge.  Lightly flour work surface; roll dough to 1/8 inch thick, using spatula to loosen dough and lightly sprinkle surface with flour as needed.  Using a cookie cutter, cut dough into desired shapes. Place 1/2 inch apart on sheets.  Or form dough into little balls, using about 1 Tablespoon each, and flattened with a greased bottom of a glass, dipped in flour from time to time.

Bake cookies, rotating sheets half way through baking until golden brown, about 6-8 minutes.  Transfer immediately to wire racks. Cool to room temperature.