Grease a 9×13 baking pan with butter, then line with parchment paper. Set aside.
In a small saucepan, heat the sugar on low heat until it’s completely melted, swirling the pan gently every 20 seconds or so. Remove from heat immediately and stir in butter. The mixture will violently bubble. You’re doing it right.
Pour in the heavy cream and sea salt. Stir until everything is combined. Use a whisk to stir in peanut butter.
Pour rice krispies into a large mixing bowl. Pour salted caramel peanut butter mixture and fold gently to combine.
Place mixture into prepared baking pan, pushing it evenly into the pan. Set aside.
Heat the chocolate chips in a double boiler over low heat until fully melted. Pour melted chocolate over the krispies, smoothing to the edges. Allow to cool completely (about 1 hour) before cutting into 2 inch squares.