Place a heatproof bowl over a small pot of simmering water.
Add the egg whites and granulated sugar to the bowl and constantly whisk until the sugar has fully dissolved about 2 minutes.
Transfer the egg whites to the bowl of a stand mixer fitted with the whisk attachment.
Whisk on medium speed until the egg whites form stiff peaks, about 4 minutes. Don’t rush this step. Just keep mixing at medium speed, and eventually, the peaks will form.
Once the egg whites have formed stiff peaks, place a fine mesh sieve over the mixing bowl and add the powdered sugar and almond flour.
Sift half of the dry ingredients into the egg whites.
Then, carefully fold the dry ingredients into the egg whites by making a J shape with your spatula. Gently fold (about 25 folds) the dry ingredients until no large lumps remain.
Then, add the second half of the dry ingredients.
Continue folding until the meringue reaches the lava stage, about 1-2 minutes of folding.
You’ll know the meringue is ready to pipe when you can draw a figure 8 without the stream breaking.
Transfer the meringue to a piping bag fitted with a small round tip.
Pipe 1” circles and pipe them at least 1.5” apart on parchment or Silpat lined baking sheets.
After you’ve piped a full tray, hold it 6” off the counter and drop it straight down to release any air bubbles. Repeat 4-5 times until it looks like any large air bubbles have popped.
Set the macarons aside to dry at room temperature for 30 minutes or until they develop a skin.
While the macarons rest, move the oven rack to the middle position and preheat your oven to 325 degrees F.
Bake the dried macarons, one tray at a time, in a fully preheated oven for 12-14 minutes or until they start to turn golden brown around the edges.
Remove the macarons from the oven and allow them to cool fully on the tray for about 45 minutes.
Bake the other tray.
Once the macarons have cooled, place them in similar-sized pairs and continue with the filling below.
MAKE THE FILLING:
Add the butter to the bowl of a stand mixer fitted with the paddle attachment.
With the mixer on low, slowly add in the powdered sugar a little at a time.
Add the pumpkin spice and vanilla when the powdered sugar is incorporated.
Turn the mixer to medium-high speed and beat until the icing is smooth and fluffy.
TO FINISH:
Transfer the filling to a piping bag fitted with your choice of tip.
Pipe a small dollop of filling onto the center of one of the macaron shells and place the other macaron shell on top.
Repeat with the remaining macarons.
Transfer the macarons to an airtight container and place them in the fridge to age overnight.
Bring the macarons to room temperature before serving.
Store in an airtight container in the fridge for up to three days.
Notes
Egg whites are a vital component of macarons, and we want them to whip into a stiff meringue, so your egg whites mustn’t have any traces of egg yolk or water in them.
The pumpkin pie spice helps make these pumpkin spice macarons! Feel free to substitute cinnamon if that’s what you have on hand.
Make sure to whisk your egg white and granulated sugar mixture constantly. You want to dissolve the sugar, but you don’t want to cook the eggs.
Adding ¼ teaspoon of cream of tartar to your egg whites and sugar can help stabilize the meringue and prevent cracking.
It’s important to whisk your meringue just until it reaches stiff peaks, Undermixing your meringue is just as dangerous as overmixing it!
Sifting the dry ingredients helps remove any large lumps, so you end up with smooth macaron shells.
You’ll know the macarons have rested enough if you can gently tap it without the meringue sticking to your finger.
If your oven bakes unevenly, you may need to flip your macaron trays halfway through baking to prevent uneven rising/browning.