In a large bowl, combine peanut butter (or other nut butter), oats, protein powder, chia seeds, and vanilla extract.
Place cashews and slivered almonds into the bowl of a food processor, then blend until finely ground, about 1 minute. Add to peanut butter mixture, then stir using a spatula until well combined. Add shaved chocolate or chocolate chips then fold into the mix. You may need to use your hands to combine it all together — if so, wet your hands slightly first.
Let mixture cool in fridge for about 20 minutes, then use your hands to roll out into 12 small bite size balls. Store in an airtight container.