Over a large mixing bowl, sift together the dry ingredients: almond flour and confectioner's sugar; set aside. Add the egg whites and granulated sugar into a mixer bowl and whisk on high speed just until stiff peaks form. A few moments before turning mixer off, add the coconut extract. Add the formed meringue to the dry ingredients. Using a large spatula, fold and mix the dry ingredients with the meringue, folding until the mixture reaches a flowing stage and settles back down on itself within 15 seconds.
Divide the batter between 2 mixing bowls. Add peach or orange colored gel food color to one of the mixing bowls, keeping the other bowl plain white.
Transfer the macaron batter into a pastry bag tipped with a large round tip. Line 2 large baking sheets with parchment paper and pipe even sized dollops of the batter onto the paper, spacing an inch apart. Use the same pastry bag for both colors. Once all cookies are piped, tap the pan against a hard surface to level the cookies and release any trapped air bubbles. Sprinkle the tops of the cookies with more ground cinnamon. Allow the cookies to stand at room temperature for 1 hour, allowing a thin shell to form on the outside.
Preheat oven to 320-325F. If you know your oven bakes at a higher temperature, set at 320F. Bake the cookies for 18-20 minutes, just until the edges are set. When cookies are baked properly, they will peel right off the parchment paper. Allow the cookies to cool on the paper for 10 minutes before transferring to a cooling rack to cool completely. Pair the cookies up according to size.
Prepare the mango puree. Peal and roughly chop 1 large mango, then place into a food processor. Pulse for a minute until fruit is pureed; add a tablespoon of lemon juice, if desired. In a small ramekin, combine the gelatin and water. Heat in microwave for 30 to 45 seconds until the gelatin is melted. Add the hot, dissolved gelatin to the fruit puree and stir until combined. Transfer the puree into a small ziplock bag or disposable pastry bag; set aside and keep at room temperature.
Prepare the coconut buttercream. Using a mixer, cream the softened butter for a 1 to 2 minutes, until light and fluffy. Add the extract and confectioner's sugar and mix again for 1 to 2 minutes, until fluffy. Transfer the buttercream into a pastry bag.
To assemble the cookies: pipe a generous amount of frosting onto one half of each pair, leaving a small well in the center for the mango puree. Add the puree into the center, then top with second half.
If desired, toast a cup of shredded sweetened coconut on a baking tray in an oven preheated to 425F. Garnish the edges of the macarons with toasted coconut by rolling each cookie on its side in the coconut flakes.