Once the chocolate chips look glossy and soft, use a small offset spatula, butter knife, or the back of a spoon to gently spread and swirl the melted chocolate over the caramel. You can create simple waves or more dramatic swirls—this is where the bars get their pretty picnic-table look.
Allow the bars to cool at room temperature until the dish is no longer hot, then transfer to the refrigerator and chill for at least 1–2 hours, or until the caramel and chocolate are fully set. This step makes slicing much neater.
When ready to serve, remove the dish from the refrigerator and let it sit at room temperature for about 10–15 minutes to soften slightly. Run a thin knife around the edges, then cut into 16 squares (or smaller bite-size pieces if serving
