Preheat oven to 325°. In a large bowl, cream butter and brown sugar until light and fluffy. Beat in egg and vanilla. In another bowl, whisk together flour, baking soda and salt; gradually beat into creamed mixture. Stir in remaining ingredients.
Drop dough by tablespoonfuls onto greased baking sheets. Bake until golden brown, about 15 minutes. Store in an airtight container. (Cookies are best after a few days.)
