Step 1

Prepare two baking sheets by lining them with parchment paper or silicone baking mats.

Step 2

Sift almond flour, powdered sugar, and ground pistachios through a fine mesh sieve into a bowl. Repeat one more time to make sure the ingredients are uniformly combined, discarding any larger pieces that don't go through the mesh sieve. Set aside.

Step 3

In a large bowl, beat the egg whites on medium speed until frothy, about 1 minute, then slowly add the granulated sugar, about 1 tablespoon every 20 seconds or so. Increase the speed to medium-high then continue to beat until stiff peaks form.

Step 4

Fold the sifted almond/pistachio mixture into the egg whites using a spatula until the batter becomes the consistency of lava and drizzles off a spatula in a thick ribbon.

Step 5

Transfer the macaron batter to a piping bag fitted with a large round tip or a ziploc bag with one corner cut off. Pipe the macaron batter in 1 1/2-inch circles onto the silpat mat or parchment paper lined baking sheets. Rap the pan against a counter a few times to release air bubbles.

Step 6

Let the macarons sit for 30-60 minutes until the top is dry enough to touch. It may take even longer if the day is humid.

Step 7

Preheat oven to 300 degrees F. Bake one sheet of macaron shells at a time for 16-18 minutes. Cool completely on the baking sheet before attempting to remove the macaron shells from the pan.

Step 8

Meanwhile, make the pistachio buttercream by beating the butter in a medium bowl until creamy and smooth. Add the powdered sugar, ground pistachios, and almond extract, then mix again. Add as much heavy cream as needed to get a good piping consistency.

Step 9

To fill the macaron shells, transfer the pistachio buttercream to a bag fitted with a piping tip or a ziploc bag with one corner cut off. Pipe buttercream onto the bottom half of the macaron shells, then top with another macaron shell.