In a food processor, grind the ingredients of the first layer: grated coconut, ground flaxseeds, almond flour, butter, vanilla, and sweetener. Once ground, you will get a loose mixture, more like soft crumbs.
In a square or rectangular mold put a layer of waxed paper. Above place the dough and crush with your fingers to cover the entire container until reaching the corners, this layer should be thick. Once extended, compress without breaking the dough. Take the mold to the freezer for about two hours.
Melt the chocolate with the butter and the sweetener in a water bath or in the microwave and once the first layer is hard, add the chocolate spreading in the same way to cover everything. Spread the chopped walnuts, if necessary, press a little so that they sink into the chocolate. Take it back to the fridge and let it cool so that the chocolate hardens.
When it is cold, remove it from the mold, sprinkle with the pinch of sea salt and cut it into squares of the size of your preference.
Enjoy.