Arrange two racks close to the oven’s center, heat to 325°F (165°C), and cover two baking sheets with parchment paper. The parchment should cover the areas where the sticky mounds will sit.

Combine the coconut with the condensed milk and vanilla in a medium bowl, then leave the mixture aside while whipping the whites. The flakes should look evenly coated and sticky rather than surrounded by loose liquid.

Whip the egg whites with the salt using an electric mixer, then gently incorporate them into the coconut mixture with a large rubber spatula. Before folding, the whites should hold straight-standing peaks when you lift the beaters.

Portion heaping tablespoons onto the lined sheets using a mini ice cream scoop or two spoons, leaving about 1 in (2.5 cm) between mounds. Each portion should hold together as a rounded mound with coconut strands visible around its surface.

Bake for 23 to 25 minutes, exchanging the pans’ upper and lower positions and turning them front to back during baking, then rest the cookies on their pans for a few minutes before moving them to a wire rack to finish cooling. Look for golden tops and edges, and handle the warm bottoms gently because they remain tender.

For the optional coating, microwave the chocolate in a microwave-safe bowl at medium power, stirring every 30 seconds, or melt it in a double boiler above simmering water. Stop heating once stirring produces a smooth, creamy consistency.

Lower each completely cooled macaroon’s bottom into the melted chocolate, let the surplus fall into the bowl, return it to the parchment, and refrigerate for about 10 minutes. The chocolate bases should be set rather than wet before you handle them.