Line your square pan with parchment paper, leaving overhang on the sides to lift out the bars easily later.
In a medium bowl, combine the toasted shredded coconut, dark chocolate chips, and sea salt, mixing well to distribute everything evenly.
In a small saucepan over low heat, melt the butter or coconut oil gently, listening for a soft bubbling sound, and stirring often until smooth and fragrant—about 3-4 minutes.
Pour the sweetened condensed milk and vanilla extract into the melted butter, stirring continuously until the mixture is smooth, shiny, and well combined.
Transfer the warm mixture into the bowl with the dry ingredients, folding gently with a spatula until everything is coated and sticky, about 2 minutes.
Spoon the mixture into your prepared pan, pressing it down firmly with the back of a spatula or your fingers to create an even, compact layer.
Optionally, sprinkle extra shredded coconut or chopped nuts on top, then press lightly to set the toppings into the surface.
Place the pan in the refrigerator or freezer and chill for at least 2 hours until the mixture is firm and set.
Once chilled, lift the set mixture out of the pan using the parchment overhang, and transfer to a cutting board.
Use a sharp knife to cut the block into 12 even squares, wiping the blade clean between cuts for neat edges.
Serve the bars chilled or at room temperature, enjoying their chewy texture and glossy chocolate finish.
