In a food processor or blender grind the walnuts to a fine texture.
Place the chocolate chips and butter in a microwave safe bowl and microwave 30 seconds at a time, stirring afterward until the chocolate is completely melted. Set aside to cool slightly.
In a mixing bowl combine the walnuts, keto chow, and powdered sweetener.
Mix the melted chocolate and butter into the dry ingredients, stir in the heavy cream and rum extract, and mix well.
Chill the mixture in the refrigerator for 30 minutes
When the mix has chilled, scoop approximately a tablespoon - a small cookie dough scoop works well for this - and shape into a ball. The texture should be like playdough. If they are too soft, refrigerate them for another 30 minutes. If they are too dry and crumbly, warm them in your hand a bit as you shape them, they should soften and come together.
Roll the balls in more powdered sweetener to coat and place them in a container to chill overnight in the refrigerator. The flavors will develop and marry as they chill.
You can also roll them in cocoa powder, ground nuts or desiccated coconut. If you want to dip them in melted chocolate, chill them for at least 30 minutes after you roll them.