Preheat the oven to 350°F. Line a large baking sheet with foil and scatter the coconut onto the pan. Bake for 6 minutes, watching the coconut carefully so it does not burn. Use tongs or a large spoon to toss the coconut together. Bake another 2 minutes and promptly remove from the oven. Let the coconut cool on the baking sheet.
In the bowl of an electric mixer, beat the butter and sugar together until just combined. Add the vanilla and mix again.
In a separate large mixing bowl, whisk together the flour and salt. Add the flour mixture and the toasted coconut to the creamed butter mixture. Mix on low speed until thick dough forms. Remove the dough to a lightly floured surface and pat into a disc. Cut in two. Using a rolling pin, roll each dough half to 1/4-inch thickness between sheets of parchment and transfer the dough inside the paper to the refrigerator. Chill for 1 hour.
Preheat the oven to 350°F. Cover two or more baking sheets with parchment paper.
When the dough is firm, remove it from the refrigerator and remove the top sheets of parchment. Cut dough into 4×2-inch fingers using a large knife. Transfer the cut-outs to the prepared sheets. Bake for 10-12 minutes, until the edges begin to turn golden and the cookies are fragrant. These cookies will spread just a little bit, this is normal.
Let cookies cool on the pan for 5 minutes before transferring to a wire rack to cool.
For the drizzle, heat the chocolate in a microwave-safe bowl at 100% power at 30 second intervals until the chocolate can be stirred smooth. Transfer the chocolate to a piping bag or a zip-top bag with the corner snipped. Drizzle dark chocolate over the cookies and let stand for 1 minute. Add tiny pinches of coarse salt on top of the cookies. Let stand until set, about 30 minutes at room temperature.
Keep cookies in an air-tight container at room temperature.