In a high speed blender or food processor, combine your shortbread cookies and walnuts, and blend until thick crumbs remain.
Transfer the mixture into a large mixing bowl. Add 1/2 cup shredded coconut, along with the melted butter, cocoa powder, powdered sugar substitute, and rum extract, and mix until combined. If the dough is too thick, add some water, one tablespoon at a time, until smooth.
Using your hands, form 12 small balls of dough. Roll each ball in the remaining coconut and place the coconut-covered balls on a lined plate or tray. Refrigerate for 30 minutes to firm up.
Notes
Water: You only need to add water if the mixture is too thick.
Tips: See my recipe tips for making the best keto rum balls.
Leftovers: Keep at room temperature for 2 weeks or in the fridge for 2 months.
Gifting: Use a glass jar or a paper box lined with parchment paper. Place the rum balls in them and refrigerate until ready to give as edible gifts.