How to Make It
In a large bowl, whisk the egg whites until frothy. Add the sugar, vanilla, and salt and continue whisking until thoroughly combined and thickened. Fold the cornflakes and coconut into the egg whites using a rubber spatula. Once combined, and using your hands, crush the cornflakes in the bowl, mi all of the ingredients together, until they stay together when you squeeze some of the mixture in your hand. Refrigerate for at least 2 hours or overnight, covering the bowl with plastic wrap. The mixture will be much easier to scoop once it has been refrigerated. The dough will keep in the refrigerator for up to 3 days.
Preheat the oven to 325°F [165°C]. Line a rimmed baking sheet with parchment paper.
Scoop 1 to 1 1/2 tablespoon of dough with a small cookie scoop or measuring spoons, making sure to really pack the batter into the scoop/spoons. Place on the prepared pan and bake for 23 to 25 minutes, until nicely browned. Sprinkle with the sea salt and let cool.
Place the melted chocolate in a zippered plastic bag, cut a very tiny hole in one corner of the bag, and drizzle the chocolate over the cookies. Let the chocolate harden before serving.
The macaroons will keep in an airtight container on the counter for up to 3 days, but they get less crunchy with each day.