Preheat oven to 350ºF. Line a baking sheet with a silicone baking mat or parchment paper.

In a very clean and dry bowl of a stand mixer, using a whisk attachment, beat egg whites on medium-high speed until foamy. Add salt, and continue to beat until they triple in volume and hold soft peaks. Continue beating while simultaneously adding sugar, 1 tablespoon at a time, until whites hold stiff peaks and look thick and glossy. Add vanilla. Turn off mixer, and fold in coconut flakes. Fold in chocolate chips, if desired.

Using an ice cream scooper, scoop macaroons onto the baking sheet 1 inch apart. Bake for 20 minutes, or until golden brown, rotating pan once halfway through baking time. Cool on trays for 5 minutes, and then transfer to a cooling rack. Store at room temperature in an airtight container for up to several days.