Heat the oven to 400F. Line a baking sheet with parchment.
Grind the coconut: Pulse the coconut in a food processor for 30 seconds, until coarsely ground. (Skip this if you are shaping your macaroons by hand instead of piping in Step 4.)
Make the batter: In a saucepan off the heat, whisk the egg whites, sugar, cocoa, and applesauce together. Stir in the coconut.
Place the pan over medium heat and cook, stirring constantly, until the mixture is pasty and hot to the touch.
Shape the macaroons: Remove the pan from the heat and scoop the macaroon batter into a piping bag fitted with a large star tip. Pipe mounds onto a parchmentined baking sheet roughly the size of walnuts in their shells.
To shape by hand without piping: Use a cookie scoop or a large soup spoon to portion out the batter.
Bake the macaroons: Sprinkle the tops with flaky sea salt and bake for about 12 minutes, until they feel dry to the touch and yield slightly to gentle pressure (they will still look glossy). Remove from the oven and cool on the sheet pan on a rack. Once cool, gently lift each macaroon off the sheet pan.