How to Make It
Make the Macaron Shells: Mix together powdered sugar and almond flour. Sift mixture into a large mixing bowl. Set aside.
In the bowl of a stand mixer, combine egg whites and salt, and whip on speed 3 until foamy, 3 minutes. Slowly stream in one-third of the granulated sugar and increase the speed to 5 for 2 minutes. Slowly stream in another third of the granulated sugar, increase the speed to 7 and whip for another 2 minutes. Finally add the last of the granulated sugar, increase the speed to 8, and whip for another 2 minutes. Add vanilla bean paste and whip for 20 seconds to combine.
Using a rubber spatula, place one-third of the whipped egg whites in the bowl with the almond flour mixture. Gently toss some of the flour mixture over the egg whites and moving the spatula under and around the egg whites, begin to incorporate the egg whites without smashing the air out. (Note: It will seem like the whites will not incorporate, but continue folding the mixture over itself and it will). After 2 to 3 minutes of folding, add another third of the egg white mixture to the dry ingredients and continue folding. Do not stir the mixture, as this will deflate the egg whites, but continue folding and it will eventually become homogenous. After a few minutes, add the last of the whipped egg whites, and continue folding. The mix will at first become a shaggy batter—continue folding until the batter falls from the spatula in a continues thick ribbon, looking like lava. If the batter falls off of the spatula in clumps, then it’s not ready. When the batter is ready, transfer to a piping bag.
Line 2 dark metal baking sheets with parchment paper and use a stencil and pencil to draw 48 circles that are 1 1/2-inch wide in diameter. Place circles at least 3/4-inch apart. Pipe the batter into each circle at a 90 degree angle directly from the middle of the circle, allowing the batter to fill the circle from its center. Once all the circles are filled, carefully hold the sides of the baking sheet and evenly slam the baking sheet against the counter 3 times. Rotate the baking sheet and do it again, this removes any pockets of air in the shells. Place the baking sheets underneath a gentle fan and allow to sit for 45 minutes.
Make the Buttercream: Heat the egg whites and sugar over a double boiler until they reach 170°F, stirring occasionally to help dissolve the sugar. Transfer to a stand mixer and whip on high until completely cool to the touch, about 7 minutes. Add butter a little at a time, whipping on medium high. Whip until satiny, 5-8 minutes. Add the vanilla bean paste and whip to combine. Transfer to a piping bag and set aside.
Finish the Vanilla Bean Macarons: Preheat oven to 325°F. Place baking sheets into the oven and immediately lower the temperature of the oven to 300°F. Bake until the shells have puffed and just begin to take on color, 15-18 minutes. Allow to cool completely on the pan before removing. Pipe buttercream on the surface of one shell and place another on top of the buttercream, gently twisting and pressing the shells together until the buttercream almost protrudes from the sides. Repeat with remaining shells and buttercream.
Macarons are best the day after they’ve been assembled, so plan ahead and make them the day before you plan to serve them.