Preheat oven to 350 F.

In a small bowl, cream butter and sugar until light and fluffy. Beat in egg.

In another bowl, whisk flour, cocoa, salt and baking soda; gradually beat into creamed mixture.

Shape dough into 1-in. balls; place 2 inches apart on ungreased baking sheets. Flatten to 2-inch rounds with the bottom of a glass.

Bake 6-8 minutes or until set (do not over bake). Cool on pans 5 minutes. Remove to wire racks to cool completely.

In a microwave, melt white chocolate with 1 teaspoon oil; stir until smooth. Drizzle over cookies. Immediately sprinkle tops with crushed candy canes; let stand until set.