1. Line a baking sheet with waxed paper; set aside.
2. In a large saucepan, combine the butter, milk, cocoa and vanilla. Cook and stir over medium heat until butter is melted and mixture is smooth. Remove from the heat; stir in cracker crumbs and 1-1/2 cups coconut. Let stand until cool enough to handle.
3. Using moistened hands, wrap about 1 tablespoon of mixture around each marshmallow (dip hands in water often to prevent sticking). Roll in remaining coconut; place on prepared baking sheet. Cover and freeze until firm. Store in an airtight container in the refrigerator or freezer. May be frozen for up to 2 months. Yield: about 3 dozen.