01 - Line an 8-inch square baking pan with parchment paper.
02 - Pulse walnuts and almonds in a food processor until finely chopped but not powdery.
03 - Add dates, cacao powder, and sea salt to the nuts and process until the mixture clumps and sticks when pressed between fingers.
04 - If using, add cacao nibs, shredded coconut, or vanilla extract and pulse briefly to mix.
05 - Press the mixture evenly and firmly into the prepared pan.
06 - Refrigerate for at least 1 hour to allow bars to set.
07 - Remove set mixture from pan, cut into 12 bars, and store in an airtight container in the refrigerator for up to 2 weeks.