Preheat the oven to 350 degrees F. Line two baking sheets with a silicone baking pat or parchment paper.

In a stand mixer, beat the butter and sugar together until light and fluffy - about 3 minutes.

Add in the salt, egg, and vanilla, then beat for another 3 minutes.

Add in the flour and cocoa powder, then mix until just combined.

Roll the dough into small 1 ½ tablespoon balls, then use your thumb to create deep indentations in the middle of each ball. Use your fingers to press together any edges that crack.

Bake the cookies for approximately 14 - 16 minutes. Use a small rubber spatula to transfer the cookies to wire racks to cool completely.

While the cookies are baking, make the filling.

In a saucepan, add the evaporated milk, sugars, and yolk together. Stir to combine, then heat on medium.

Stir the mixture until it begins to bubble and thicken. Remove from heat and add in the butter, vanilla, coconut, and pecans. Allow the mixture to cool until it is just warm to the touch,

Fill the indentations of the cookies with the filling. Pack the filling in and let it mound over a bit.

Drizzle the tops of the cookies with the melted chocolate and allow to cool until the chocolate is hardened.