Line a 9 x 6 x 2-inch baking dish with parchment paper and set it aside.
In a large bowl, combine the puffed brown rice, almonds, sunflower seeds, pumpkin seeds, hemp seeds, and cinnamon.
In a separate bowl, whisk together the cashew butter, honey, and melted coconut oil until smooth.
Pour the wet mixture over the dry ingredients. Use a silicone spatula to mix everything until well combined.
Transfer the mixture into the prepared baking dish. Press it down firmly and evenly into the dish using your hands or the back of a spatula.
Melt the dark chocolate chips in a microwave-safe bowl, microwaving in 30-second intervals and stirring until fully melted.
Drizzle the melted chocolate over the bars. Refrigerate for 30 minutes to set.
Sprinkle the flaky sea salt on top, then refrigerate for another 30 minutes until the chocolate hardens.
Carefully slice the bars into 4 x 1-inch pieces using a sharp knife. Store in an airtight container in the fridge for up to two weeks or freeze for up to three months.