Preheat oven to 350F. Cream butter and 1/4 cup sugar; add egg. Beat till light and fluffy. Beat in puree and vanilla. Stir together flour, salt, and cinnamon; stir into creamed mixture. Form dough into the shapes you like. Place cookies on greased cookie sheet and bake until slightly browned, about 20 minutes. Remove from pan; cool on rack. Melt chocolate chips in double boiler over low heat. Dip one end of each cookie in chocolate; place on waxed paper until set.