To make the shells
To make the shells, line two large baking sheets with a silpat mat or parchment paper. Fit a piping bag with a small, round tip (I like a Wilton #10 or #12).
Make a double boiler by placing a heatproof bowl over a small saucepan of simmering. Make sure that the bottom of the bowl doesn’t touch the simmering water but rests above it.
Add the egg whites and granulated sugar to the bowl and whisk continuously until the sugar has fully dissolved. This will take 4 to 5 minutes. To test if the sugar is dissolved, dip a fingertip into the mixture and rub the finger against your thumb. If the sugar has dissolved, you won’t feel any graininess.
Transfer the egg whites and sugar to the bowl of a stand mixer fitted with the whisk attachment. Beat the egg whites on medium-high speed until they form stiff peaks. This will take a few minutes.
Sift the powdered sugar and almond flour through a fine-mesh sieve into the egg whites. Fold in the mixture gently with a rubber spatula to incorporate the flour and sugar into the egg whites without deflating them. Make sure to scrape all the way to the bottom of the bowl while you fold.
Smush the batter against the sides of the bowl and fold it back together until the meringue flows smoothly. When the meringue is ready to pipe, you should be able to draw a figure 8 without the stream breaking.
Transfer the meringue to the piping bag fitted with the round tip. Pipe 1-inch macarons about 2 inches apart on the prepared baking sheet.
Once you’ve finished piping a sheet pan full of macarons, lift the pan a few inches off the counter and drop it straight down to release any air bubbles. Repeat lifting and dropping 4 to 6 times, or until it appears that any large air bubbles have popped.
Allow the macarons to sit, uncovered, at room temperature for about 30 minutes to dry them out.
Preheat the oven to 325°F.
Bake the macarons one tray at a time for 14 minutes, turning the tray half way through cooking. Repeat with the second tray.
Allow the macarons to cool fully before removing them from the tray.
To make the filling
In the bowl of a stand mixer fitted with the paddle attachment, beat the butter on medium-high speed for 1 to 2 minutes, or until the butter is light and fluffy.
With the mixer on low, slowly add the powdered sugar. Once all of the powdered sugar has been added, add the chocolate and mix to combine. Scrape down the sides of the bowl and turn turn the mixer to medium-high speed and beat until the buttercream is light and airy, about 2 minutes. Transfer the mixture to a piping bag fitted with your choice of tip.
In a small bowl, stir together the coconut, pecans, and caramel and set aside until ready to use.
To assemble
Place the macarons in similar sized pairs. Pipe a small ring of chocolate buttercream onto the flat size of one of the macarons. Fill the center with the coconut-pecan mixture and gently press another macaron on top, just until the icing reaches the edges. Transfer the macarons to an airtight container and place them in the fridge to age overnight. Bring to room temperature before serving.