Preheat oven to 350°. Whisk the first 6 ingredients until blended. In another bowl, toss coconut with flour; stir in egg white mixture., Drop by tablespoonfuls 2 in. apart onto greased baking sheets. Bake until tops are light brown, 15-18 minutes. Remove from pans to wire racks to cool completely., Dip bottoms of macaroons into melted chocolate, allowing excess to drip off. Place on waxed paper; let stand until set. Store in an airtight container.