Preheat oven to 325°F and line a baking sheet with parchment paper.

Add coconut flakes, dulce de leche and vanilla in a medium-sized mixing bowl. Use a rubber spatula to combine.

In the bowl of a stand mixer fitted with the whisk attachment, whip the egg whites on high speed until stiff peaks form. Gently fold the egg whites into the coconut mixture.

Using a cookie scoop, place compacted scoops (about 1.5 tbsp) of the mixture onto the prepared baking sheet, at least 1 inch apart.

Bake for 20 minutes, rotating the pan halfway to ensure even baking. Remove from oven and allow macaroons to cool for 10 minutes on the baking sheet before transferring to a wire rack to cool completely.

Melt the chopped chocolate in a double boiler or microwave. Dip the bottom of each cooled macaroon into the melted chocolate and place onto a parchment-lined baking sheet. Drizzle remaining chocolate over the tops of each cookie and sprinkle with flaked sea salt. Allow chocolate to set at room temperature or in the refrigerator.