Cream together softened butter and sugar. Add egg and vanilla and stir in well. Stir in flour and salt.

Cookies can be made right away by placing rounded spoonfuls of dough onto cookie sheet.

Bake at 350 degrees until edges of cookies just start to turn color.

Alternatively, dough may be refrigerated. Either roll cookies into golf-ball-sized balls before baking or refrigerate dough in a long roll wrapped in wax paper and slice cookies before baking.