Cover a rimmed baking sheet with foil and spray with baking spray. Place graham crackers to make a single layer. Cover with popcorn, macadamia nuts and puffed rice cereal.
In a small saucepan, bring butter and sugar to a boil over medium -high heat. Let boil and stir one time, reduce the heat to low and let mixture become a golden brown syrup, swirling occasionally.
Pour toffee mixture over the graham crackers evenly, bake until slightly darkened in color, approximately 10 to 12 minutes.
Take out of the oven and sprinkle with chocolate chips and smoked flaky sea salt. Let cool completely before breaking bark into chunks.