01 - Line an 8-inch square baking pan with parchment paper, leaving an overhang for easy removal.
02 - Pulse walnuts and oats in a food processor until finely chopped but not powdery. Add dates, almond butter, maple syrup, and sea salt. Process until mixture clumps and holds together when pressed.
03 - Press mixture firmly and evenly into prepared pan. Use back of spoon or hands for an even layer.
04 - Melt dark chocolate and coconut oil together in heatproof bowl over simmering water (double boiler) or microwave in 30-second increments until smooth.
05 - Pour melted chocolate over base and spread evenly with spatula. Sprinkle chopped walnuts and flaky sea salt over chocolate.
06 - Refrigerate for at least 1 hour or until chocolate is completely set.
07 - Lift bars out using parchment overhang. Cut into 16 squares with sharp knife. Store in airtight container in refrigerator for up to 1 week.