Melt the dark chocolate in a double broiler or in a microwave.
Mix the melted chocolate with cashew butter, hazelnut butter, and vanilla. Mix until smooth.
Add the protein powder and mix until fully incorporated. The batter will be quite thick.
Divide into 12 silicone mini muffin tins OR scoop into 12 balls and place on a silicone sheet pan. Refrigerate for 15 minutes, or until the chocolate is set. Remove from the muffin tins or sheet pan and store in an airtight container in the fridge or freezer.