Preheat the oven to 350° and line a baking sheet with parchment paper. In a bowl, whisk the egg whites with the sugar and 1 teaspoon of the vanilla until the sugar is mostly dissolved. Add the coconut flakes and toss to coat. Spread the coconut on the baking sheet in an even layer and bake for about 25 minutes, stirring frequently, until golden and fragrant. Let cool completely, then break the crispy coconut into small pieces.