Preheat oven to 325°. Line 2 baking sheets with silicone liners or parchment paper.
Heat approximately half of chocolate chunks in a small saucepan until just melted. Remove from heat and stir in remaining chocolate chunks. Stir to melt. Set aside.
In a food processor fitted with the steel blade, blend the coconut for a full minute. Add sugar and cocoa powder; blend another minute.
Add eggwhites, table salt and vanilla and blend until combined. Add the melted chocolate and blend again until smooth and fully combined.
Using a scoop or spoon, portion 1" mounds of dough on lined cookie sheets. Cookies can be spaced closely as they don't spread much, just puff up a bit.
Bake 15 minutes, until shiny and just set. Immediately after they come out of the oven, sprinkle with flaky sea salt. It doesn't take much, but adds a really nice contrast. Cool completely on the baking sheet. Store in an airtight container at room temperature.