Place egg whites in a medium bowl, and let stand at room temperature for exactly 3 hours. (Aging egg whites in this manner is essential to creating perfect macarons.)
Line 2 rimmed baking sheets with parchment paper. Using a pencil, draw 48 (1½-inch) circles 2 inches apart on parchment paper. Turn parchment paper over.
In a large bowl, sift together confectioners’ sugar, almond meal, and salt.
Beat together egg whites and cream of tartar with a mixer at medium-high speed until foamy. Gradually add granulated sugar and coconut extract, beating at high speed until stiff peaks form, 3 to 5 minutes. (Egg white mixture will be thick, creamy, and shiny.) Gradually and gently fold in almond meal mixture, one-third at a time. Let batter stand for 15 minutes.
Transfer batter to a piping bag fitted with a medium round tip (Wilton #12), and pipe batter onto drawn circles on prepared baking sheets. Tap baking sheets on counter 5 to 7 times to release air bubbles. Let stand at room temperature for 1 hour before baking to help develop the macaron’s signature crisp exterior when baked. (Macarons should feel dry to the touch and not stick to the finger.)
Preheat oven to 275°.
Bake until macarons are firm to the touch, approximately 20 minutes, rotating baking sheets halfway through. Let cool completely on baking sheets. Transfer macarons to an airtight container with layers separated by wax paper. Refrigerate for up to 3 days until ready to fill and serve.
Place Mango Filling in a piping bag fitted with a medium round tip (Wilton #12). Pipe filling onto flat side of 24 macarons, and top with remaining macarons, flat sides together. Lightly push down and twist so filling spreads to edges. Serve immediately.
Recipe by TeaTime Magazine at https://teatimemagazine.com/coconut-mango-macarons/