For the macarons: Sift the almond flour with the powdered sugar in a bowl.
In a saucepan on high heat, bring the granulated sugar and 3 tablespoons water for the syrup to 230 degrees F on a candy thermometer, 3 to 5 minutes. When the sugar syrup reaches about 190 degrees F, start whipping 2 egg whites. Whip until they reach full peaks, and then slowly add the boiling syrup. Continue to whip on medium-high speed until they are completely cooled and you have a shiny meringue, about 10 minutes.
Mix the remaining 2 egg whites and the sifted almond/sugar and carefully fold into the meringue.
Preheat the oven to 320 degrees F. Line baking sheets with silicone baking mats.
Fill a pastry bag fitted with a plain tip with the meringue and pipe macarons about 3 inches in diameter on the prepared baking sheets. Tap the baking sheets to get rid of any air bubbles, and let dry out at room temperature for about 10 minutes. (Optional: Blow some disco dust or edible glitter on top of the macarons before tapping, to give them a shimmer.)
Bake for 12 to 18 minutes, depending on your oven. Check to see if the macarons are done by grabbing the top of one macaron and trying to shake it. They are done when the top barely slides against the skirt. If they are not done, extend the baking time by 2 minute intervals, checking after each extension. Allow to cool fully before trying to take them off the baking sheet.
For the buttercream: Cook the 1/2 cup sugar and corn syrup with 1/2 cup water, without agitating it, to a dark amber color, or about 400 degrees F on a candy thermometer. Deglaze with the cream and whisk together off the heat to obtain the caramel sauce. Allow to cool to room temperature.
Bring the remaining 1 cup sugar and 1/2 cup water to a boil in a small saucepan. Cover with a lid or plastic wrap and let boil for 2 to 3 minutes. Remove the lid and cook the sugar to 244 degrees F, 3 to 5 minutes.
While your syrup is boiling, whip the whites on medium speed of your stand mixer to soft peaks. This is a timing issue, so watch them carefully. Adjust the speed of the mixer up or down and try and get your whites to the perfect consistency at the same time your sugar reaches 244 degrees F.
When the syrup is ready, with the mixer on medium-low speed, pour the syrup in a thin stream down the inside of the mixing bowl. This will give the syrup a chance to cool off a bit as well as keep the syrup from getting spun all over the sides of the mixer by the whisk attachment. Turn the mixer to high and whip until the whites are completely cool and hold firm peaks, about 10 minutes.
Add the butter, a bit at a time, making sure one addition is blended in before adding the next. At the very end, add the caramel sauce and salt, as well as the salt and bourbon into your buttercream.
To assemble: Fill a piping bag with the buttercream at room temperature (if it's refrigerated, paddle in the mixer while torching the side until it comes back together).
Fill the center of the macaron cookie, and sandwich the top with another cookie until they look like little burgers.