Line your square pan with parchment paper, allowing a slight overhang for easy removal.
Crush the graham crackers into fine crumbs using a food processor or by placing them in a zip-top bag and pounding with a rolling pin.
In a small saucepan, melt the butter over low heat until it’s just shimmering and fragrant, about 2 minutes.
Combine the crushed graham crackers with the melted butter in a bowl, mixing until evenly coated and crumbly.
Press the crumb mixture firmly into the prepared pan, creating an even crust about half an inch thick. Use the back of a spatula or your fingers to smooth the surface.
Chill the crust in the fridge for 10 minutes while you prepare the caramel layer.
In the same saucepan, pour in the sweetened condensed milk and caramel sauce, then stir over low heat. Cook gently, stirring constantly, until the mixture thickens slightly and turns a rich golden color, about 3-4 minutes.
Pour the warm caramel mixture over the chilled crust, spreading evenly with a spatula. If desired, sprinkle a pinch of sea salt flakes on top for contrast.
Let the bars sit at room temperature for 5 minutes, then transfer to the fridge to set for at least 2 hours or overnight for best results.
Once set, lift the bars out of the pan using the parchment overhang. Use a sharp knife to cut into squares, wiping the blade between cuts for clean edges.
If desired, melt some chocolate and drizzle over the bars for an extra indulgent finish. Serve and enjoy these sticky, sweet, and satisfying no-bake caramel bars!
