Combine first 4 ingredients in a 6-quart slow cooker. Cook, covered, on LOW 1 hour and 30 minutes or until vanilla bark and chocolate look very soft. Uncover and stir until smooth. Stir in pretzels, crackers, and crushed peppermint candies.
Drop candy by heaping tablespoonfuls onto wax paper. Let stand 1 hour or until firm.