Line a 9x13" rimmed baking sheet with parchment paper and set aside.
Use a food processor to finely chop the Nilla Wafer cookies, then add them to a large mixing bowl.
5 cup Nilla Wafers
Repeat the food processing with the walnuts, adding them also to the cookie crumbs in the mixing bowl.
1 cup Walnuts
Add the powdered sugar, cocoa powder, and salt to a fine mesh sieve. Using a spoon, sift the powdered sugar and the cocoa powder into the mixing bowl of cookie crumbs and walnuts. The sieve will break up any lumps in the powdered sugar and cocoa.
1 cup Powdered sugar, 2 tablespoon Cocoa powder, ½ teaspoon Salt
In a small mixing bowl, mix the corn syrup and rum. The corn syrup will help 'glue' the rum balls together.
2 tablespoon Corn Syrup, ½ cup Rum
Pour the rum mixture into the bowl with the cookie crumb mixture. Mix the rum into the cookie crumb mixture and blend until combined.
Form 1" inch balls from the cookie crumb dough. Place each cookie ball on the parchment lined cookie sheet, and set in the refrigerator for 15 to 30 minutes to firm up.
Roll each cookie ball in a shallow plate filled with cocoa powder, powdered sugar, or chopped nuts as a coating. You can also roll the balls in sprinkles, or any other decorative garnish.
Garnish