Preheat the oven to 350 degrees F, and line an 8x8 inch square baking pan with parchment paper. Do not skip the parchment paper; it's very important for clean, easy removal of the bars.
Make your graham cracker crumbs by placing broken up sheets of graham crackers in a powerful blender or food processor. Pulse until the crackers become small crumbs. If you don't have a blender or processor, put the sheets in a ziploc bag and use a rolling pin or bottle to crush them. Measure out the specified amount and toss it into the prepared baking pan.
Add melted butter and salt to the crumbs. Stir them together with a fork, until the mixture resembles wet sand. Use the palm and back of your hand to press the crumbs into a flat, uniform crust.
In a medium bowl, combine dulce de leche and a splash of milk. Stir together with a spatula or spoon. We're just doing this to make the dulce de leche slightly thinner. Be careful not to add too much milk.
Now, we'll begin layering the bars. Start by sprinkling chocolate chips over the prepared graham cracker crust. Then, add coconut flakes, and finish it off with the chopped pecans.
Drop dollops of the dulce de leche on top of the layers of chocolate, coconut, and pecans. Use a spatula or the back of a spoon to spread the milk caramel as evenly as you can. It will be thick and very sticky. Don't worry about spreading the dulce de leche to every corner, or pressing it down too much into the pan, because it will spread and liquify as it bakes.
Bake in the preheated oven for 28-30 minutes. The dulce de leche will be slightly bubbling, and the edges will be golden brown. Even though it's finished baking, the caramel will still look pretty wet and gooey. That's okay.
Remove the bars from the oven, sprinkle a little coarse sea salt over the top, and allow them to cool in the pan, uncovered, for AT LEAST 3 hours before slicing into squares or diamonds. Do not attempt to cut or remove the bars until they are sufficiently cooled.