Preheat oven to 350ºF. Line cookie sheets with parchment paper.
Beat butter and sugars in the bowl of an electric mixer fitted with the paddle attachment on medium speed until pale and fluffy, 2 minutes. Beat in eggs, one at a time, until combined, then beat in vanilla.
In a large bowl, whisk together flour, salt, baking soda, and baking powder. With mixer on low, gradually add to butter mixture, beating until well combined. Add oats, coconut, and dark chocolate and beat until just combined.
Drop cookies by tablespoonfuls onto prepared cookie sheets. Bake 9-11 minutes, until golden but still slightly under-baked. Let cookies cool on pan 2 minutes before transferring to a wire rack to cool completely.