Line a baking sheet with parchment paper. In a microwave-safe bowl, combine the unsalted butter and natural peanut butter. Microwave for 20 to 30 seconds until melted. Stir in the powdered sweetener and vanilla extract until smooth.
Add the peanut flour and stir until a stiff dough forms. If the dough feels too sticky, add a little more peanut flour.
Using clean hands, roll the dough into 1-inch balls and place them on the prepared baking sheet. Freeze the balls for 1 hour until firm.
Melt the chopped dark chocolate with the coconut oil in a microwave-safe bowl using 30-second intervals and stirring in between until smooth. If needed, add more oil until you achieve a consistency that allows for dipping.
Dip each frozen ball into the melted chocolate, allowing the excess to drip off before placing it back on the sheet. Allow the chocolate to set completely before serving.