Line a 12-cavity muffin tin with cupcake liners and set aside.
In a bowl, combine the walnut (or other nut) butter, coconut oil, maple syrup, vanilla, and salt until smooth.
Scoop out a scant ¼ cup of the walnut mixture and place in a small bowl. Set aside.
Spoon the walnut mixture evenly into the 12 cavities of the lined muffin tin.
Add cacao powder to the small bowl and stir well until smooth.
Spoon one teaspoon of the cacao mixture onto each of the cups. Swirl the cacao mixture into the walnut concoction with a small knife or toothpick.
Place in freezer until firm. Serve and enjoy a nutty, chocolatey treat!