Pulse sandwich cookies in a food processor until ground; transfer to a bowl. Mix cream cheese into ground cookies.
Combine 1/2 cup walnuts, cranberries, and coconut in food processor; pulse until ground and evenly combined. Stir mixture into cookie mixture. Roll mixture into balls, about 1 tablespoon each. Poke a toothpick into each ball and arrange on a baking sheet; freeze until solid, 1 to 2 hours.
Melt white chocolate in a microwave-safe glass or ceramic bowl in 15-second intervals, stirring after each melting, 1 to 2 minutes.
Dip frozen balls in the melted chocolate. Arrange truffles in a baking sheet or insert toothpick into a piece of Styrofoam(R). Sprinkle chopped walnuts over truffles.