In a heavy saucepan over low heat melt the chips with the condensed milk. Stir constantly to avoid burning.
Gradually add crumb mixture and nuts to the melted chocolate mixture. Mix well.
Let stand at room temperature for 30 minutes. To speed this process up, you can chill in refrigerator.
Shape into 1 inch balls. Dip in chocolate and place on wax paper to set up.
NOTE: They have the small paper baking liners---I think they call them mini muffin baking liners. These are a great way to serve the rum balls and are attractive when using this as a gift. I store them in an air tight container for up to 2 weeks. I've also substituted pecans for the walnuts in this recipe. Both are good--so it really is a personal preference or nut availability.