Preheat oven to 350º F. Line a large baking sheet with parchment paper and set aside.
In a mixer or large mixing bowl, combine egg whites, maple syrup, vanilla extract, and sea salt. Whisk (or use a whisk attachment) to combine until light and foamy. Do not mix until stiff peaks form. If you overmix the egg whites, no worries! Just stir the coconut in for a longer time and it will deflate.
Add the coconut into the egg white mixture, and stir to fully coat the coconut.
Allow the coconut mixture to sit and rest for 30 minutes prior to forming the macaroon cookies. This allows the coconut to absorb the liquid and results in lighter, better textured cookies. I recommend you do not skip this step (the cookies will be crumbly if this step is skipped).
Use a 1-tablespoon cookie scoop to make cookie balls, and add them to the prepared baking pan. Make sure to really press the coconut mixture into the scoop tightly.
Bake the macaroon cookies for 13-16 minutes, until lightly golden brown on top. Allow the cookies to fully cool – and if planning to coat in chocolate, I find it easiest to freeze the cookies for about 30 minutes prior to dipping in chocolate.
Add dark chocolate, coconut oil, and optional peppermint or almond extract to a double boiler to melt the chocolate. Heat over medium heat, stirring often, until the chocolate is fully melted, then remove from heat.
Dip the base of each coconut macaroon in the dark chocolate mixture, then return to the baking sheet.
Add the remaining chocolate to a piping bag, and drizzle over the tops of each cookie, if desired.
Allow the chocolate to set in the refrigerator or freezer prior to serving the macaroons.