Preheat oven to 350°. Cream butter and sugar until light and fluffy; beat in egg and vanilla. In a separate bowl, whisk flour, baking soda and salt; gradually beat into creamed mixture. Stir in popcorn, chocolate chips and pecans.
Drop by tablespoonfuls 2 in. apart onto greased baking sheets. Bake until golden brown, 13-14 minutes. Remove to wire racks to cool.